v0.7.3

This release includes compatibility fixes for different ruby versions
and some minor enhancements.

• C Extensions are only compiled on MRI 1.9.x.

  For MRI >= 2 the native API is used, so this should speedup
  installation.

  For JRuby this will avoid crashes on gem installation.

  This was alredy being checked for Rubinius.

  Amadeus Folego

• Added experimental JRuby support for 1.7.x series.

  Only the main API is implemented and Binding#eval is
  monkey-patched as it is private on JRuby.

  This requires the compiler to be run on interpreted mode,
  otherwise an exception will be thrown when of_caller is called.

  Charles Nutter

• Improve JRuby support over 0.7.3pre1. Chris Price

• Remove executability from non-executable files.

  David Celis

• Test and notice MRI 2.1 as a working Ruby implementation.

  Lennart Fridén

• Remove global mri_2? method. Akira Matsuda

• Test on MRI 2.2 through 2.4. Omer Katz, John Mair