update to latest QT which fixes #1573
update CHANGELOG
add support for incremental builds
use OpenSSL 1.0.1g for the windows builds
rename the msvc2010 target to msvc-winsdk71 in the build script
use wildcards in the OpenSSL configuration for MSVC
add support for building using MSVC 2008-2013
update to the latest QT

This fixes #1586 and includes compilation fixes for MSVC 2012/2013
fix detection of the MSVC x64 compiler in the build script
update to the latest QT which fixes #1631
add support for specifying flags for each target in the build script
add support performing a clean build
support debug builds for MSVC targets in the build script
update to the latest QT which fixes #1512
use highest compression level for XZ in the build script

This reduces file sizes to almost 50% of their previous values
remove the unmaintained OS X build script
remove hack for MSVC 2010 as it is no longer needed
sync VERSION with the download folder on SourceForge
do not fail if building from a non-git checkout
use the version passed from the build script in the qmake configuration

If it is not available, we fallback to reading the VERSION file.