Parse CMake version strings containing '-'

[jllllll]

Uses a simple str.split('-msvc') to extract the version number. '-msvc' in particular was chosen to allow for forwards-compatibility with future builds of MSVC CMake. I did not check for older versions as I do not expect they will be any less compatible and this is still an improvement on the current situation of no compatibility at all.

In my opinion, splitting on - should be sufficient and provide compatibility with any other builds of CMake with custom version strings. However, I did not do this as I'm not familiar with all of the possible builds of CMake out there and wanted to ensure functionality.

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Update: Now parses using str.split('-') for extended compatibility. Thanks @henryiii

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Resolves: #500