x64: add support for some x87 instructions
Jit64[IL]: fix float conversions

Floating-point is complicated...

Some background: Denormals are floats that are too close to zero to be
stored in a normalized way (their exponent would need more bits). Since
they are stored unnormalized, they are hard to work with, even in
hardware.  That's why both PowerPC and SSE can be configured to operate
in faster but non-standard-conpliant modes in which these numbers are
simply rounded ('flushed') to zero.

Internally, we do the same as the PowerPC CPU and store all floats in
double format. This means that for loading and storing singles we need a
conversion. The PowerPC CPU does this in hardware. We previously did
this using CVTSS2SD/CVTSD2SS. Unfortunately, these instructions are
considered arithmetic and therefore flush denormals to zero if non-IEEE
mode is active. This normally wouldn't be a problem since the next
arithmetic floating-point instruction would do the same anyway but as it
turns out some games actually use floating-point instructions for
copying arbitrary data.

My idea for fixing this problem was to use x87 instructions since the
x87 FPU never supported flush-to-zero and thus doesn't mangle denormals.
However, there is one more problem to deal with: SNaNs are automatically
converted to QNaNs (by setting the most-significant bit of the
fraction). I opted to fix this by manually resetting the QNaN bit of all
values with all-1s exponent.
Interpreter: fix float conversions

Can't use simple casting, otherwise we get the same problems as in Jit64.
Re-enable non-IEEE mode support
x64Emitter: Add the xmm, xmm form of PSRLQ instruction.
x64Emitter: Fix the PSUBQ instruction's opcode
Interpeter: Fixed ConvertToDouble to match the manual.

Also added some documntation comments.
Silence some Windows compiler warnings

by adding explicit type casts.
DSP: remove redundant expression
DSP: add inline opcode documentation

While further increasing the table width doesn't make the code any less
ugly, it makes it easy to generate auto-comments in the IDA processor
plugin. Also, use spaces for alignment instead of tabs.
Convert all includes to relative paths.
Fix Linux build
Dolphin now builds on Linux with only Source/Core as include dir
Merge pull request #79 from Tilka/nits

Silence some Windows compiler warnings
Save frame skipping option, and allow loading it from game ini too.
Scope the Windows include directory to only point to Source/Core/.

Also fix the Windows build with this change.
Fix the OSX build.

Turns out Dolphin uses some macros that clash on OSX. However thankfully, this include is only used in Frame.cpp.
Merge pull request #87 from RachelBryk/save-frame-skip

Save frame skipping option, and allow loading it from game ini too.
Add an automated tool that does basic checking of includes sort order.
Fix more header sorting issues in Common/ (now check-includes clean).