Updated GM_setValue and GM_getValue calls to set based on a keyword-userID-digplotID key. This should fix the bug where users running multiple browsers/private tabs got synchronized settings across tabs. This has the added benifit of saving values per digplot, so that it will remember what you were working on if you switch.
Wrote explicit IF block for Precise/Rugged so that it will not attempt Precise work (and print an error to console) when Rugged is selected.
