Added initial nimcheck plug-in - a command plug-in which runs the current view through 'nimrod check'
Allow user to choose an error to go to. Clean up code.
Rename nimchecker.py to NimCheck.py

Add the 'check file' command
Clean up the checking code
Cleaned up nimcheck core logic (modularized it mainly)

Added an 'external file check' command, which checks external, unopened files.