Catch broken configurations inside of the Post Processing shaders.

This catches most instances of configuration failures that can happen in a post processing shader.
Gives a user a helpful error message that lets them know what they have failed to set up correctly
Switch from disabling a laundry list of warnings for wxWidgets to just disabling everything, since they're almost certainly not our problem and I want to compile with -Werror.
Remove unused declarations.
Reduce my idiocy in register saving code.

(1) Rename ABI_ALL_CALLEE_SAVED to ABI_ALL_CALLER_SAVED, because that's
what it was actually defined as (and used as).  Derp.

(2) RegistersInUse is always used for the purpose of saving registers
before calling a C++ function in the middle of a JIT block (without
flushing).  There is no need to save callee-saved registers in this
case.  Change the name to CallerSavedRegistersInUse and mask with
ABI_ALL_CALLER_SAVED.

Nothing obvious broke when starting up a Melee game.  (I added a test
for anything actually being masked out; it happens, but in this
particular case seemed to occur at most a few dozen times per second, so
the actual performance benefit is probably negligible.)
DolphinWX: Move the CodeView debugger view over to wxGraphicsContext

This is a more advanced drawing 'backend' over the previous one and allows us to control things like transparency and anti-aliasing, etc.
DolphinWX: Parenthesize some expressions in CodeView.cpp
Fix bloody printf specifiers.

In particular, even in code that only runs on x86-64, you can't use
PRIx64 for size_t because, on OS X, one is unsigned long and the other
is unsigned long long and clang whines about the difference.  I guess
you could make a size_t specifier macro, but those are horribly ugly, so
I just used casting.

Anyone want to make a nice (and slow) template-based printf?

Now without bare 'unsigned'.
Improve wording of a particularly atrocious message.

(Now without gettextize.)
Merge pull request #859 from comex/doubleclick

Improve wording of a particularly atrocious message.
Merge pull request #861 from comex/warnings

Fix warnings for OS X
Merge pull request #862 from comex/registersinuse

Reduce my idiocy in register saving code.
Remove unused variable m_zero.
Merge pull request #866 from comex/warnings2

Remove unused variable m_zero.
Merge pull request #828 from Sonicadvance1/pp-shader-catch-broken-config

Catch broken configurations inside of the Post Processing shaders.
Revert "Catch broken configurations inside of the Post Processing shaders."
Merge pull request #872 from dolphin-emu/revert-828-pp-shader-catch-broken-config

Revert "Catch broken configurations inside of the Post Processing shader...
JIT: fix incredibly silly mistake in fmul rounding patch
Merge pull request #865 from lioncash/debugger-stuff

DolphinWX: Use wxGraphicsContext in the Code View for the debugger.
Merge pull request #874 from FioraAeterna/fixidiocy

JIT: fix incredibly silly mistake in fmul rounding patch
Rename Log2 and add IsPow2 to MathUtils for future use

Also remove unused pow2/pow2f functions.