Floating point support

[RealKC]

Adding support for working with floating point would be nice.

Changes needed:

• add the instructions and registers to the specification.
• figure out how to make the floating point and stack interactions work
• add opcode and registers definitions to common/opcodes.hpp and common/registers.hpp
• make the VM aware of the new opcodes and registers
• make the assembler be able to emit bytecode making use of these new registers and opcodes.

Design questions:

• Should the VM only support extend to 64-bit floating-point numbers(i.e. double in C++), or 32-bit floating-point numbers(i.e. float in C++) as well?
• How many registers should be added?