Changes in Conv*, Ld* and St* opcodes so that values with size < 4 bytes are extended to 4 bytes.
Implemented Not and Xor for values with size 8 bytes.
Added tests for bitwise operations, arithmetic operations and Conv* opcodes.
- Fixed Single.ToString() on special cases (infinities, NaN and 0) and aumented the range of printable values
- Fixed Double.ToString(): it always printed "Double Overrange" for a bug in opcode ldarga
- Fixed opcode ldarga: the displacement of the argument variable was off of 4 bytes
- Fixed opcodes shr, shr_un and shl when the shift was more that 32 bytes, added to BCL relative tests
- Added BLC tests regarding BitConverter and unsafe code
- Moved the meat of the code of Single.ToString() and Double.ToString() to the class StringHelper together with the analogous methods for numer types
- Re-added _floatsignbit to CosmosAssembler.cs so the neg test should not fail anymore
- Removed all code relative to x87 that I had left under #if false
- Clean up
