Added initial version of lab1.
Fixed error in use of movia.

- Removed invalid commas from after the movia instruction.
Update the .gitignore file

- Update .gitignore to ignore swap files and nios_macros.s.
Added the two in-lab instructions.
Created named constants for opcodes.

- Named opcodes eliminates use of "magic numbers", making the
  emulated program easier to read.