Development Thread Testers wanted: float conversion fixes

[flacs]

phire and I have cooked up a few patches that correct how Dolphin converts between different floating-point formats. Previously, converting single->double->single would not always yield the original value which broke games that use floating-point instructions for copying arbitrary data. This was also the reason why adding support for non-IEEE mode broke so many games.

Please test the following Dolphin version:
Windows 64 bits | Windows 32 bits | Mac
Linux: no package available, please see https://code.google.com/p/dolphin-emu/wiki/Linux_Build
anything ARM: not impacted

Some ideas of what to test (but any feedback is welcome):
- Please report anything that breaks compared to the version on which this branch is based.
- At least all the bugs referenced in the non-IEEE mode master issue should be fixed (probably older ones too, please report if you find any).
- Try different PPC emulation backends (JIT recompiler, JIT IL recompiler, interpreter).
- Run on different physical CPUs with different SSE/AVX support.

Note: A slight slowdown (< 10%) is to be expected. Rest assured that we have already made compromises for increased performance.

[quinneypoo]

Wow 10% performance hit is huge, can you make this an option in settings? Or is that not an option?

[ExtremeDude2]

Did you test it?

[neobrain]

Wow 10% performance hit is huge, can you make this an option in settings?

No.

[quinneypoo]

Wow 10% performance hit is huge, can you make this an option in settings?

No.

Is there a technical reason why? Or you just don't want another option in Dolphin?

[delroth]

Yes: the old behavior is objectively wrong.

[Silanda]

I can't say I've tested it much but this fixes the Sonic Unleashed loading problems with no additional problems noted in anything I've thrown at it so far.