[PATCH] AVI frame dump on every VI

[sgrunt]

This patch against r7093 dumps frames on every VI such that the AVI video output is a constant 60 (or 50) FPS. (The patch also sets the output frame rate properly based on NTSC/PAL.)

Using this and my previously-written audio dumping patch, it's now possible to get a synced video/audio dump using only the emulator. (There are some residual sound timing issues which I have yet to trace, but this can be fixed by adding an appropriate delay at the start of the sound track - current working estimate is 1 second).

[boogerlad]

Yay! I guess I won't need taksi for dolphin anymore.

[Toad King]

Just a note: Rather than having a bunch of precompiler conditions to cast the image data as a signed char in Windows, you can just change the Windows version of AVIDump to accept unsigned chars to prevent that. It gets re-cast anyway.