fixing build issue with WCoverArtLabel - do not use 'promote' logic
Now it is inserting the custom label in a boxlayout directly in the dlgtrackinfo class
fixing bug introduced by last changes - storing scaled cover in the correct member
Remove unused msvshacks build option.
Various MSVC build changes in preparation for actually making debug builds.

* Merge build-type and msvcdebug build options.
* Move some out-of-place stuff out of Optimize feature.
* Misc. updates to indicator flags in mixxx.py.
DlgCoverArtFullSize - adding WindowStaysOnTopHint flag
Define PROTOBUF_USE_DLLS when not building with static dependencies on Windows.
Fixes to SCons Windows SDK and compiler configuration.

* Warn about using the SCons MSSDK tool.
* Disable SCons MSVC detection entirely by specifying MSVC_USE_SCRIPT as None.
* Add an mssdk_dir scons flag -- explicitly add Bin, Lib and Include sub-folders to the environment with support for x64 sub-folders (which the SCons MSSDK tool does not have).
Support lib, include, and bin sub-folders of the WINLIB folder.
Update MSVC++ runtime installation.

* Distribute the runtime executable installer instead of an MSI.
* Remove hacky util.get_mssdk_path() since it essentially picks an SDK at random if you have multiple installed.
* Update NSIS to use MSVC2013 runtime registry key.
Remove arbitrary ATL include path. We already do this in the new MSSDK support code.
Use the ATL in XP-compatibility mode.
Windows XP compatibility: Use /subsystem:WINDOWS,5.[01|02].

See: http://blogs.msdn.com/b/vcblog/archive/2012/10/08/windows-xp-targeting-with-c-in-visual-studio-2012.aspx?PageIndex=2
We don't use phonon.
Tabs -> spaces.
Use the configured QTDIR, not the environment QTDIR.
Print relevant environment variables so they are recorded in the build log (will help with debugging user build issues).
Condition round definition on _MSC_VER < 1800 since MSVC 2013 includes C99 support.
Include algorithm.h for sd::min/max definitions.
Update SoundSourceOpus to build on Windows.
Remove msvc filter in DLL glob expression (it doesn't actually work) and also glob DLLs in the 'lib' sub-folder.