#246880 by mr.baileys: Fixed Error when adding duplicate category to contact form module (with tests).

- Patch #572618 by effulgentsia, pwolanin, sun: all theme functions should take a single argument. Code clean-up and performance improvement. Woot.

before a form builder function, to facilitate common form elements. Clean-up
from form_builder changes from CTools patch. Has nice side-benefit of making
all form functions' signatures consistent.

#504428 follow-up by keith.smith: Remove 'now' from all empty admin screen texts. Steve Krug would be proud.

- Patch #276581 by catch: wrote missing tests for contact module and simplified contact module thanks to that.  Also removed some whitespace.

- Patch #245115 by kkaefer, John Morahan, JohnAlbin et al: after a long discussion we've decided to make the concatenation operator consistent with the other operators.

#100641 by kkaefer, ChrisKennedy and RobRoy: change 'Submit' buttons to 'Save' to compliy with the desktop metaphor and actually tell what the button does ('we know it submits the form, but what it does?')