Add Erubi to doc/TEMPLATES.md

Adjust ERB and Erubis documentation.  Remove mention of Less and
BlueCloth as both are deprecated.

docs/TEMPLATES.md

@@ -14,20 +14,20 @@ which are guaranteed to work across all the implementations. If you wish to be
 compatible with all of these template classes, you should only depend on the
 cross-implementation features.
 
- * [ERB](#erb) - Generic ERB implementation (backed by erb.rb or Erubis)
+ * [ERB](#erb) - Generic ERB implementation (backed by erb.rb, Erubis, or Erubi)
  * [erb.rb](#erbrb) - `Tilt::ERBTemplate`
  * [Erubis](#erubis) - `Tilt::ErubisTemplate`
+ * [Erubi](#erubi) - `Tilt::ErubiTemplate`
  * [Haml](#haml) - `Tilt::HamlTemplate`
  * [Liquid](#liquid) - `Tilt::LiquidTemplate`
  * Nokogiri - `Tilt::NokogiriTemplate`
  * Builder - `Tilt::BuilderTemplate`
  * Markaby - `Tilt::MarkabyTemplate`
  * [Radius](#radius) - `Tilt::RadiusTemplate`
 
-Tilt also includes support for CSS processors like [LessCSS][lesscss] and
-[Sass][sass], [CoffeeScript][coffee-script] and some simple text formats.
+Tilt also includes support for CSS processors like [Sass][sass],
+[CoffeeScript][coffee-script] and some simple text formats.
 
- * Less - `Tilt::LessTemplate`
  * Sass - `Tilt::SassTemplate`
  * Scss - `Tilt::ScssTemplate`
  * CoffeeScript - `Tilt::CoffeeScriptTemplate`
@@ -44,7 +44,6 @@ implementations (depending on which are available on your system):
  * [Markdown](#markdown) - Generic Markdown implementation
  * [RDiscount](#rdiscount) - `Tilt::RDiscountTemplate`
  * Redcarpet - `Tilt::RedcarpetTemplate`
- * BlueCloth - `Tilt::BlueClothTemplate`
  * Kramdown - `Tilt::KramdownTemplate`
  * Pandoc - `Tilt::PandocTemplate`
  * CommonMarker - `Tilt::CommonMarkerTemplate`
@@ -55,8 +54,9 @@ ERB (`erb`, `rhtml`)
 --------------------
 
 ERB is a simple but powerful template languge for Ruby. In Tilt it's backed by
+[Erubi](#erubi) (if installed on your system) or by
 [Erubis](#erubis) (if installed on your system) or by [erb.rb](#erbrb) (which
-is included in Ruby's standard library). This documentation applies to both
+is included in Ruby's standard library). This documentation applies to all three
 implementations.
 
 ### Example
@@ -84,7 +84,7 @@ Or, use `Tilt['erb']` directly to process strings:
 Omits newlines and spaces around certain lines (usually those that starts with
 `<%` and ends with `%>`). There isn't a specification for how trimming in ERB
 should work, so if you need more control over the whitespace, you should use
-[erb.rb](#erbrb) or [Erubis](#erubis) directly.
+[erb.rb](#erbrb), [Erubis](#erubis), or [Erubi](#erubi) directly.
 
 
 #### `:outvar => '_erbout'`
@@ -93,6 +93,11 @@ The name of the variable used to accumulate template output. This can be
 any valid Ruby expression but must be assignable. By default a local
 variable named `_erbout` is used.
 
+#### `:freeze => false`
+
+If set to true, will set the `frozen_string_literal` flag in the compiled
+template code, so that string literals inside the templates will be frozen.
+
 <a name='erbrb'></a>
 erb.rb (`erb`, `rhtml`)
 -----------------------
@@ -104,8 +109,9 @@ All the documentation of [ERB](#erb) applies in addition to the following:
 ### Usage
 
 The `Tilt::ERBTemplate` class is registered for all files ending in `.erb` or
-`.rhtml` by default, but with a *lower* priority than ErubisTemplate. If you
-specifically want to use ERB, it's recommended to use `#prefer`:
+`.rhtml` by default, but with a *lower* priority than ErubiTemplate and
+ErubisTemplate. If you specifically want to use ERB, it's recommended to use
+`#prefer`:
 
     Tilt.prefer Tilt::ERBTemplate
 
@@ -124,20 +130,9 @@ following characters:
   * `'%'`  enables processing of lines beginning with `%`
   * `true` is an alias of `<>`
 
-#### `:safe => nil`
-
-The `$SAFE` level; when set, ERB code will be run in a
-separate thread with `$SAFE` set to the provided level.
-
-#### `:outvar => '_erbout'`
-
-The name of the variable used to accumulate template output. This can be
-any valid Ruby expression but must be assignable. By default a local
-variable named `_erbout` is used.
-
 ### See also
 
-  * [ERB documentation](http://www.ruby-doc.org/stdlib/libdoc/erb/rdoc/classes/ERB.html)
+  * [ERB documentation](https://docs.ruby-lang.org/en/master/ERB.html)
 
 
 <a name='erubis'></a>
@@ -151,7 +146,7 @@ All the documentation of [ERB](#erb) applies in addition to the following:
 ### Usage
 
 The `Tilt::ErubisTemplate` class is registered for all files ending in `.erb` or
-`.rhtml` by default, but with a *higher* priority than `ERBTemplate`. If you
+`.rhtml` by default, but with a *lower* priority than `ErubiTemplate`. If you
 specifically want to use Erubis, it's recommended to use `#prefer`:
 
     Tilt.prefer Tilt::ErubisTemplate
@@ -172,24 +167,48 @@ When `true`, `Erubis::EscapedEruby` will be used as the engine class
 instead of the default. All content within `<%= %>` blocks will be
 automatically html escaped.
 
-#### `:outvar => '_erbout'`
+#### Other
 
-The name of the variable used to accumulate template output. This can be
-any valid Ruby expression but must be assignable. By default a local
-variable named `_erbout` is used.
+Other options are passed to the constructor of the engine class.
 
-#### `:pattern => '<% %>'`
+### See also
+
+  * [Erubis Home][erubis]
 
-Set pattern for embedded Ruby code.
 
-#### `:trim => true`
+<a name='erubi'></a>
+Erubi (`erb`, `rhtml`, `erubi`)
+---------------------------------
+
+[Erubi][erubi] is a ERB implementation that uses the same algorithm as
+[Erubis][erubis], but is maintained and offers numerous improvements..
+
+All the documentation of [ERB](#erb) applies in addition to the following:
+
+### Usage
+
+The `Tilt::ErubiTemplate` class is registered for all files ending in `.erb` or
+`.rhtml` by default, with the *highest* priority.
+
+    Tilt.prefer Tilt::ErubisTemplate
 
-Delete spaces around `<% %>`. (But, spaces around `<%= %>` are preserved.)
+__NOTE:__ It's suggested that your program `require 'erubi'` at load time when
+using this template engine within a threaded environment.
+
+### Options
+
+#### `:engine_class => Erubi::Engine`
+
+Allows you to specify a custom engine class to use instead of the
+default which is `Erubi::Engine`.
+
+#### Other
+
+Other options are passed to the constructor of the engine class.
 
 ### See also
 
-  * [Erubis Home][erubis]
-  * [Erubis User's Guide](http://www.kuwata-lab.com/erubis/users-guide.html)
+  * [Erubi Home][erubi]
 
 
 <a name='haml'></a>
@@ -459,7 +478,6 @@ Markdown formatted texts are converted to HTML with one of these libraries:
 
   * [RDiscount](#rdiscount) - `Tilt::RDiscountTemplate`
   * Redcarpet - `Tilt::RedcarpetTemplate`
-  * BlueCloth - `Tilt::BlueClothTemplate`
   * Kramdown - `Tilt::KramdownTemplate`
   * Pandoc - `Tilt::PandocTemplate`
   * Maruku - `Tilt::MarukuTemplate`
@@ -535,10 +553,10 @@ using this template engine within a threaded environment.
   * GitHub: [rtomayko/rdiscount][rdiscount]
 
 
-[lesscss]: http://lesscss.org/ "Less CSS"
 [sass]: http://sass-lang.com/ "Sass"
 [coffee-script]: http://jashkenas.github.com/coffee-script/ "Coffee Script"
-[erubis]: http://www.kuwata-lab.com/erubis/ "Erubis"
+[erubis]: https://github.com/kwatch/erubis "Erubis"
+[erubi]: https://github.com/jeremyevans/erubi "Erubi"
 [haml]: http://haml.info/ "Haml"
 [liquid]: http://www.liquidmarkup.org/ "Liquid"
 [radius]: http://radius.rubyforge.org/ "Radius"