Rename the poorly named {Read,Write}BigEData to Copy{From,To}Emu -

and change argument order to match memcpy.

Oh, and fix a lulzy buffer overflow in IOS emulation while I'm at it.
Merge pull request #1343 from comex/yet-another-stupid-branch

Rename the poorly named {Read,Write}BigEData to Copy{From,To}Emu -