Some work on upgrading our (third-party) binaries, now that Qt 5.3.1 has been released (#380) [ci skip].

There seems to be an issue with the EGL library not being found on
Linux. So, right now, we only have new binaries for Windows and OS X.
Done with upgrading our (third-party) binaries, now that Qt 5.3.1 has been released (closes #380) .

The issue with Qt 5.3.1 on Linux has been filed (see
https://bugreports.qt-project.org/browse/QTBUG-39859).
Some minor cleaning up [ci skip].
Some minor cleaning up [ci skip].
Some minor cleaning up [ci skip].