Pass modifier to mouse events for click/dblclick

A fix for the issue described here:

https://github.com/ariya/phantomjs/issues/11867
Update some grammar on the README.md

Replaces the "a, b, c, d" with the more grammatically correct "a, b, c, and d"
Adding tests for #11867

This tests mousedown, mouseup, click, and doubleclick for clicks with
modifier events. The mousedown/mouseup tests pass in 1.9.2, the
click/doubleclick do not. All pass with a build from this branch.
Merge pull request #11868 from bradleyboy/click-modifier-fix

Pass modifier to mouse events for click/dblclick
Fix CoreText performance note on OS X 10.9 (Mavericks).

Upstream Qt bug: https://bugreports.qt-project.org/browse/QTBUG-32789
Upstream patch: https://codereview.qt-project.org/#patch,all,70097,4.
Upstream commit: https://qt.gitorious.org/qt/qt/commit/98352b964f

https://github.com/ariya/phantomjs/issues/11418
Fix warning of obsolete userSpaceScaleFactor on OS X 10.9 (Mavericks).

Related upstream bug: https://bugreports.qt-project.org/browse/QTBUG-28574

Issue #1162 https://github.com/ariya/phantomjs/issues/11612