fixing multi selection handling for various emacs commands

Conflicts:
	lib/ace/keyboard/emacs.js
emacs: fix multi select exchangePointAndMark

Conflicts:
	lib/ace/keyboard/emacs.js
emacs: cleanup
emacs/isearch: select when moving cursor via isearch and emacs mark is set
emacs: fix exchangePointAndMark in normal select mode
emacs: make code strict conform
isearch: being flexible about whether emacs mode is on or not
isearch test: ensure multi select
adding improvements as suggested by @nightwing
emacs: improved multi selection handling for emacs mark
fix emacs universal argument
Merge remote-tracking branch 'remotes/origin/emacs'

Conflicts:
	lib/ace/incremental_search_test.js