Tabbed control interface

Added tabbed section to controls input (functions, loops, constants) as basis for further work. Also set position to fixed, and mended numerous resulting bugs.
This is the second version (previous used links instead of radio buttons, but was found to be fundamentally limited and so no pull request was sent)

No javascript has been changed or added; functionality should be entirely unchanged.

Next few steps:
-Add remaining buttons
-Update button layout
-Add functionality to buttons (array)
-Add functionality to run (array->arduino) (will need testing for this, and probably help with the arduino code)
-Add ability to move and/or delete elements in array/list
-(eventually)Add option for textual input
-Make generally pretty and wonderful