Updated CHANGELOG and whats_new.rst: with (re-)generate auto-legend
in Qt4Agg backend.
As requested in https://github.com/matplotlib/matplotlib/pull/2947#issuecomment-41059777

(Fix of Issue #2934)
Updated whats_new.rst: Wording of figureoptions doc
Merge remote-tracking branch 'anykraus/figureoptions-generate-simple-legend'

Conflicts:
	CHANGELOG