Don't indent on return if the cursor is positioned at left of program text.

Fixed https://github.com/jdf/Processing.py-Bugs/issues/81
Build 0372.
Permit the use of hand-rolled or single-jar libraries in Python Mode.

Fixes https://github.com/jdf/Processing.py-Bugs/issues/98
Build 0373.
Source cleanup pass.
Improve "mixed mode" detection and reporting.

Recognize size() as a function that can't be called at top level in
active mode.

Report line number and offending function name in mixed mode error.

Fixes https://github.com/jdf/Processing.py-Bugs/issues/107
Build 0374.