Merge tag '0.5.4' into develop
New release cycle.
Merge tag '0.5.4.1' into develop
Merge tag '0.5.4.2' into develop
Merge tag '0.5.4.3' into develop
Minor cleanups
Command line options cleanup

* Added 3.4 as supported Python version, it mostly works with the next
  release.

* New option group for backend compiler choice

* New option group for Windows specific stuff.

* Recommend clang 3.2 or higher
New pre-release.
Fix, use "uintptr_t" instead of "intptr_t" as it is more appropiate.

* This is most likely the cause of Issue#146.

* For very large addresses, the sign bit may make a difference when
  casting to "unsigned long" later.
Added assertion that generator is valid when starting it.

* This should be triggered for Issue#146 as it must be assumed that
  the generator is not good anymore.
Standalone Python3 Windows: Use the designated code to read the file.

* This function takes care of different encodings and should be used.

* The UTF-8 assumption for standard library doesn't hold on Windows
  for at least.
Added test for Issue#145 but currently not enforced.

* Classes with prepared dictionaries don't get those dictionaries written to until
  the very end, which is not compatible.

* Will need refactorings of class body variables, so this is delayed.
Added assertions and precautions to fiber layer

* Detect if an invalid object is used to prepare a fiber.

* Make sure we don't ever accidentally double free.
Fix, make sure to check for non re-vival of the generator at the very end.
Minor cleanups
Fix, was setting line numbers for internal source references in frames.

* This corrupted stack callbacks for with statements where the "__exit__"
  handler raised an exception.

* It's also unnecessary code bloat and performance loss potentially due
  to missed out optimizations.
RHEL5: Detect the compiler from the gcc44 package automatically.

* Also white list a warning given from the linker about 32 bits library
  when linking 64 bits binary.

* Makes it easier to use with EPEL python26/python26-devel packages.
Fix, where necessary use integers to makecontext instead of unsigned long.

* Channeling a pointer through makecontext does not work on all systems,
  x86_64 is the currently know offender, there may be others. Also depends
  on what libc does.

* Reconstruct at call site the pointer value from the integers.

* Apparently at least RHEL5 x64_86 is having a different libc implementation
  or address space randomization that will make it visible.
Tests: Added test case of threaded generators, cleanups

* From Issue#146 where it crashed on some platforms.

* This is to make sure we can handle this everywhere.

* Adapted CPytho32 for the many CPython related crashes on Windows.
Minor cleanups