Fix WebKit build with MSVC 2013

- MSVC 2013 includes a number of math functions which were missing from
earlier versions of MSVC. See
https://qt.gitorious.org/qt/qtscript/commit/24d678ce9c3996f46d1069c2b1193e7ec1083fc8

- MSVC is unable to automatically handle certain implicit casts in
HashSet.h. Fix based on patch linked to on discussion at QTBUG-28335 and
QTBUG-28335
Implement Windows support in Mendeley/Qt config script

Port the Mendeley configuration script to Python for ease of working
across Mac, Linux, Windows and add configuration options required for
Windows

OpenSSL needs to be built separately on Windows. The configure script
contains instructions for doing that.
Mark mendeley-release-configure.py as executable
Add option to build only x64 version on Mac

For development builds, 32bit libs are not required.