- Implement KiTrap19 handler (XMMI exceptions, mostly copied KiTrap7 handler and...

- Implement KiTrap19 handler (XMMI exceptions, mostly copied KiTrap7 handler and used mxcsr status word and exceptions there). There will be no weird 0xF BSODs anymore, however I need to investigate about exceptions masking.
- Dynamically enable it, if CPU supports XMMI (was already done in the kernel, but #if0-ed).

svn path=/trunk/; revision=29406