Added immediate versions of several arithmetic operations

- These immediate versions make it possible to perform some operations without
  wasting the limited instruction size afforded to an iris program.
Implemented arithmetic immediate operations in libiris
Added immediate support to the assembler
Added example2.iris

- This example takes advantage of the new immediate arithmetic operations
Updated documentation to reflect the new insns
Imported maya base into iris
Added interact.c, clips <-> iris bridge
Repl is now a separate tool
Updated the repl

- Iris is now displayed
Removed implemented interact funcs

- Eliminated implicit registers as they are hopelessly complex. I've hardcoded
  register indices instead.
- Eliminated redundant or duplicate typedefs
- started using stdint.h for the purposes of uint32_t and uint16_t