MSVC Projects: Add project templates for cogl-path

This adds template project files that is used to build cogl-path, where the
source files can be filled in using autotools. Note that although cogl-path
is built as a static library, items to build DLLs for this is intentionally
left in there as this is intended to be a shared library later.
Update Visual Studio Property Sheets

-Add items to generate the enumeration sources
-Add items to build the CoglPath library, which was split out
-Make the header installation up to date, especially due to the split out
 of Cogl-Path
Visual Studio Projects: Use Custom Build Rules

Use custom build rules to generate the enumeration sources and the .def
files so that the IDE will regenerate those files upon change and clean
them when a clean up request is requested.

Also make the projects reflect more closely the file layout in the
current source tree