Merge pull request #318 from mike42/development

 Changes for release 1.5.1

README.md

@@ -87,7 +87,8 @@ Many thermal receipt printers support ESC/POS to some degree. This driver has be
 - Excelvan HOP-E801
 - Excelvan ZJ-8220
 - Gainscha GP-5890x (Also marketed as EC Line 5890x)
-- Gainscha GP-U80300I
+- Gainscha GP-U80300I (Also marketed as gprinter GP-U80300I)
+- gprinter GP-U80160I
 - Hasar HTP 250
 - Metapace T-1
 - Okipos 80 Plus III
@@ -99,6 +100,8 @@ Many thermal receipt printers support ESC/POS to some degree. This driver has be
 - Star TSP100 ECO
 - Star TSP-650
 - Star TUP-592
+- SPRT SP-POS88V
+- Xprinter F-900
 - Xprinter XP-Q800
 - Venus V248T
 - Zjiang NT-58H
@@ -138,6 +141,20 @@ git clone https://github.com/mike42/escpos-php vendor/mike42/escpos-php
 require __DIR__ . '/vendor/mike42/escpos-php/autoload.php';
 ```
 
+#### Requirements
+
+To maintain compatibility with as many systems as possible, this driver has few
+hard dependencies:
+
+- PHP 5.3 or above
+- `mbstring` extension, since the driver accepts UTF-8 encoding.
+
+It is also suggested that you install either `imagick` or `gd`, so that you can
+print images.
+
+A number of optional packages can be added to enable more specific features. These
+are described in the "suggest" section of [composer.json](https://github.com/mike42/escpos-php/tree/master/composer.json).
+
 ### The 'Hello World' receipt
 
 To make use of this driver, your server (where PHP is installed) must be able to communicate with your printer. Start by generating a simple receipt and sending it to your printer using the command-line.

composer.json

@@ -18,12 +18,17 @@
     },
     "require": {
         "php": ">=5.3.9",
-        "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^3.8"
+        "ext-mbstring": "*"
+    },
+    "suggest": {
+        "guzzlehttp/guzzle": "Allows the use of the ApiConnector to send print jobs over HTTP.",
+        "ext-imagick": "Will be used for image printing if present. Required for PDF printing or use of custom fonts.",
+        "ext-gd": "Used for image printing if present."
     },
     "require-dev": {
         "phpunit/phpunit": "4.8.*",
-        "squizlabs/php_codesniffer": "2.*"
+        "squizlabs/php_codesniffer": "2.*",
+        "guzzlehttp/guzzle": "~3.0|~4.0|~5.0|~6.0"
     },
     "autoload": {
         "psr-4": {