Not all non-volatile registers were actually saved and restored, leading to a few registers being trashed after calling the vm instructions.
All non-volatile registers have been added.
- Clean up ftol()/snapvector() mess
- Make use of SSE instructions for ftol()/snapvector() if available
- move ftol/snapvector pure assembler to inline assembler, this will add x86_64 and improve support for different calling conventions
- Set FPU control word at program startup to get consistent behaviour on all platforms