DVD emulation: make seek timing more accurate.

Based on real measurements of a Gamecube disk on a Wii.  (If anyone else
is interested in running more tests, I can upload my code; it's a mess at
the moment.)

This isn't a complete model, but it's a step in the right direction:
in Metroid Prime, the loading times are sane, and I think I managed to do it
without breaking anything.
DVDInterface: tweak buffered reads to be a bit faster.

A read finishes when the result is complete in the drive's buffer, not
main memory.
DVDInterface: code cleanup.
Opcode decoding: 0xC0 isn't a valid command.

Fix our opcode decoders to handle this appropriately.
Opcode decoding: handle missing opcodes 0x88 etc.

Hardware testing shows that they do the same thing as the 0x80 family of
opcodes: they draw quads.
Video backends: fix rounding in lighting computation.

For whatever reason, the hardware doesn't do a full divide by 255, but
instead uses an approximation with shifting, similar to the way it is done
in TEV.
OGL/VertexManager: Remove unnused m_CurrentVertexFmt
Use size_t in std::string operations in IniFile.cpp, not int
make IOCTL_SO_GETHOSTID more accurate on Windows
remove unused and unexported function
Video backends: fix behavior of "konst" TEV inputs.

Also fixes TEVCOLORARG_HALF.

Values verified to match hardwarere.
changed IOCTL_SO_GETHOSTID to remove malloc()/free() calls
account for GetIpForwardTable() returning ERROR_MORE_DATA
remove trailing whitespace
Video backends: unify xfregs/xfmem structures.

Removes the duplicate swxfregs global variable/struct from the software
backend in favor of the ones from VideoCommon.
Video backend: merge global var xfmem into xfregs.

There isn't really any reason to keep them separate.
Video backends: mass-replace "xfregs" with "xfmem".
VideoCommon: cleanup Renderer::RecordVideoMemory.
Video backends: warn on usage of GL_DRAW_QUADS_2.

It's not normally used, so if it shows up, it could indicate a CPU emulation
bug.
Move bn.h and ec.h into the correct filter section
CheckExceptions: add TODO and remove a wrong comment