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.

Store _StubMsg in the frame structure since it's needed for exception handling.

It should be a float, not an HRESULT.

Based on patch from Sergey Khodych.

oleaut32: Make _argsize and _xsize receive the full TYPEDESC and parent ITypeInfo, use a different function in IDispatch code.