Teach the VS 2015 generator to support WindowsStore 10.0 applications.
Add target properties to customize them:
* VS_WINDOWS_TARGET_PLATFORM_MIN_VERSION: Specifies the minimum version
of the OS that the project can target.
* VS_DESKTOP_EXTENSIONS_VERSION, VS_MOBILE_EXTENSIONS_VERSIONS,
VS_IOT_EXTENSIONS_VERSION: Add a reference to the version of the SDK
specified to the target allowing to target the extended functionality in
a universal project.
* VS_IOT_STARTUP_TASK: Specifies that the target should be
built as an IOT continuous background task.
Add a VS_DEPLOYMENT_LOCATION source file property to specify where to
put files that are part of the package. For example:
set_property(SOURCE ${ASSET_FILES} PROPERTY VS_DEPLOYMENT_LOCATION "assets")
Without this, sources marked with VS_DEPLOYMENT_CONTENT cannot be
located properly.
Create properties VS_SHADER_ENTRYPOINT and VS_SHADER_MODEL. Without
these many .hlsl source files may not be possible to use. Extend the
VSWinStorePhone test project to cover them.