- Fix a bug in KeRaiseUserExceptionDispatcher which was causing us not to set the...

- Fix a bug in KeRaiseUserExceptionDispatcher which was causing us not to set the Exception Address (EIP) in the EH record.
- Fix a terrible stack corruption bug in KeRaiseUserExceptionDispatcher which was causing us to eventually fuck up the stack in user mode (0x14 bytes instead of 0x50 bytes were reserved).
- Protect User-mode Callbacks with SEH, and use STATUS_POP_CALLBACK_STACK.
- Fix another nasty stack corruption bug in user-mode APC delivery.
- Protect User-mode APC delivery with SEH.
- Fix SEH handlers to return EXCEPTION_EXECUTE_HANDLER isntead of ExceptionContinueSearch.

svn path=/trunk/; revision=24173