Migrate to QScriptContext

Migrated sys.sendAll, sys.sendMessage,  +most of file operations

These now throw script errors instead of printing warnings when they fail.
Scripts will need to be updated (where they don't check for a file existing) or players manually create blank files on first run of some scripts.

Extra shorthand names:

writeToFile          -> write
appendToFile         -> append
deleteFile           -> rm
getFileContent       -> read
getCurrentDir        -> cwd
makeDir              -> mkdir
removeDir            -> rmdir

Drafted: sys.broadcast