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.
- Removed GetHashCode() methods that were not really needed
- Plugged class CultureInfo for GetHashCode()
- Plugged class Runtime.CompilerServices for GetHashCode()
- Plugged class RuntimeTypeImpl for GetHashCode()
- Fixed tests that were failing using true .NET GetHashCode()
- Fixed IL Interpreter added SHIFT, AND, XOR... for sbyte and short
