Merge pull request #2 from agraef/master

More fixes for compatibility with Arch Linux.
fixed bug where scrollbars were drawn/displaced incorrectly in K12 mode
made scrollbars more sensitive
improved appearance of mknob (using tkpath), improved accelerated behavior, added undo awareness
revamped iemgui nlet color detection by embedding var in t_text
cosmetic fix to properties
expanded t_text to include te_iemgui var that determines whether an external has a custom gui