Implement extended instruction set functions

[almarklein]

• [x] Implement the infrastructure
• [x] Refactor a bit so that function names are part of co_call instruction rather than loaded from the stack.
• [x] Implement and test some functions:
  • [x] pow
  • [x] sqrt
  • [x] length
  • [x] abs
  • [x] min, max, clamp
  • [x] ... and 37 more :)
• [x] (self) review
• [x] remove dead code (see the 1 / 0 that is never touched)