It can easily replaced by rb_ary_entry().

Also make use of StringValueCStr() where it is suitable.

This should fix: https://github.com/larskanis/fxruby/issues/24

rb_during_gc() isn't sufficient for indication of free-phases on Ruby < 2.2.
In some sitiations it returns zero, altought being within a free-phase.
Moreover Rubinius doesn't support rb_during_gc() at all.

So we now use both, rb_during_gc() and our own GC-detection, to avoid calls
that are prohibited while GC phases.

This reverts commit acec4416.

Only the address of the foxobj is checked, but this is ambiguous
for the first member of a struct or class like this:

struct FXAPI FXMaterial {
  FXVec4f    ambient;           // Ambient material color
  FXVec4f    diffuse;           // Diffuse material color
  FXVec4f    specular;          // Specular material color
  FXVec4f    emission;          // Emissive material color
  FXfloat    shininess;         // Specular shininess
};

One and the same address point to a FXMaterial and a FXVec4f object.

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

so that all FXTRACE() and FXASSERT() calls are skiped, per default.

This should improve performance.

This fixes https://github.com/larskanis/fxruby/issues/21
It was introduced in commit 347966fc.

This fixes issue https://github.com/larskanis/fxruby/issues/20

This should ensure, that the event is definitely cleared.

These functions should be thread safe.

Switch off polling-based (addChore) processing of threads

Add event-based interruption of GVL-released functions.

This works for sockets only for now.

This is the only function that is currently required to acquire the GVL.
Other FXRbCall functions could be wrapped equally.

This is just enough for loadPixel/savePixel, but if other methods
release the GVL, potentially all other callback functions could
be called. These are now yet wrapped by gvl-aware wrappers.

This also fixes some build system checks, that should be for the target system.

without check.

This solves crashes of kind:
	[BUG] rb_gc_mark(): 0x00000003f54af8 is T_ZOMBIE

All parameters to Ruby event blocks or overloaded methods are converted to
proper Ruby classes or wrapped by appropriate wrapper classes for borrowed
objects. The wrapper classes are registered, to keep the connection between
C-pointer (the borrowed object) and the wrapping Ruby object. This connection
is canceled either when the borrowed object is destroyed or the Ruby wrapper
is free'd. If neither of them happens, the wrapper object is re-used for the
next call.

This worked good with Ruby-1.8, which has one big mark and sweep run.
Ruby-2.2 introduced incremental GC and has several mark and sweep runs, so
that marks and sweeps are quite independent. Therefor we re-used objects,
that are already maked for sweeping (so called T_ZOMBIE).

This patch releases the connection between borrowed object and it's wrapper
object after each call into Ruby code. Therefore the wrapper object isn't
re-used, but a new one is created for each param to each call. The wrapper
objects are later free'd by the GC. This patch could have a negative
performance impact.

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