0.9.0

Although the version number increased by quite a bit this release in itself is
fairly small. Seeing how the ruby-lint internals are slowly becoming more and
more stable I'd like the version numbers to correspond with that. I'm not
jumping to 1.0 right away since I do want to make various changes to the
internals before I release 1.0.

Having said that, this release contains the following:

• Caching of ASTs required for finding externally defined constants.
• An extra CLI command (plot) for plotting analysis timings.
• Method call tracking.
• Warnings for unused method/block arguments.
• Support for Rubinius 2.0.

The two most noteworthy changes are the caching system and support for method
call tracking, these are highlighted below.

Caching

In previous releases ruby-lint would re-parse extra files needed (those that
contain the definitions of referenced constants) every time you'd analyze a
file. This was rather problematic since [parser][parser] sadly isn't the
fastest kid on the block. By caching the resulting ASTs performance of the same
file (assuming it doesn't change between runs) can be increased drastically. If
the analyzed file or an external one is changed the cache is invalidated
automatically.

Caching is enabled by default so you don't need to add any extra command-line
flags or configuration options in your ruby-lint configuration file.

Method Call Tracking

This new features makes it possible for ruby-lint to keep track of what methods
are called from another method, both in the direction of caller to callee and
the other way around. Currently this isn't used yet for any analysis but I have
some ideas on adding useful analysis using this new feature. Another use case
for this feature is generating Graphviz call graphs without actually having to
run the corresponding Ruby source code.