C++ DLLs built with i586-mingw32msvc and i686-w64-mingw32 are not compatible.

So this changes the build, so that we ship the ports directorys of both
compiler versions.

This fixes https://github.com/larskanis/fxruby/issues/22

Switch off polling-based (addChore) processing of threads

Add event-based interruption of GVL-released functions.

This allows to safely execute GUI code from other threads.

Static linking all dependent libraries into each ruby version (from
1.8 to 2.2) would blow up the gem to >20MB.

This way it also works for derived classes like FXJPGImage.

Before commit af543822 loading order of fox16.so and fox16.rb was irrelevant.
But now fox16.rb must be called, in order to load ruby files to the C++
extension. Renaming the C++ extension ensures, that fox16.rb is called first.

Allow more consistent read/write access to image data, that is also
usable with derived classes like FXJPGImage.

Moreover much faster String based access to the pixel data is possible,
now.

FXImage#data and FXMemoryBuffer is now deprecated.

whitespaces

Replace PLATFORM with RUBY_PLATFORM and respect other platforms, too. Fixes http://rubyforge.org/tracker/index.php?func=detail&aid=28740&group_id=300&atid=1223