Note that using GL_DEPTH_COMPONENT instead of eg. GL_DEPTH_COMPONENT24
will work, but will create a renderbuffer with the format of the
onscreen depth buffer.

Spotted by Jeremy White.

Avoids special casing all over the place.

imm32: Implement helper functions for copying CompositionString data out of the IME. Standardize ImmGetCompositionStringA/W to use a common T function.

RegExp part of patch is based on Mozilla regexp implementation.