PVM interpreter implementation

[asmie]

The basic implementation of Polka VM.
PVM instancing, execution and host-functions.

From the Matrix:

Every project is expected to implement. However, since M1 and M2 do not have any performance requirements, you can get away with implementing a simple interpreter, which shouldn't take too long (Jan managed to implement it in less than 24 hours).

Test vectors (PRed):
w3f/jamtestvectors#3

Tasks:

• Parse program blob feat: parse PVM program blob #43
• Execute and run code
  • Instantiate the program
  • Set/Get to registers
  • Store/Load to memory
  • Branch/jump
  • Execute external functions
  • Compute basic operations such as add/multiply/divide/shift/and/or/xor etc
  • Jump indirect
  • sbrk
• Implement Gas
• Implement tracing
• tests

Pre-start condition:

• PVM research task