date-773271: Inputter.setInput should move cursor to end

Previously, by ignoring caretChange, the default was to move to the next
argument, which was really arbitrary. Now it does the obvious thing of
moving the cursor to the end of the input.

Signed-off-by: Joe Walker <jwalker@mozilla.com>
date-773271: Fix broken TZ assumption

We now use UTC hours (etc) to detect a midnight time (from which we
assume day accuracy) rather than testing for ISOStrings which were
localised.

Signed-off-by: Joe Walker <jwalker@mozilla.com>
date-773271: Add more unit tests for dates

Signed-off-by: Joe Walker <jwalker@mozilla.com>