Allow shared

[mattyclarkson]

This branch adds a few things:

• Prevent users configuring in the source folder. This prevents untracked files being present in the git repository.
• Allows the user to build shared libraries if they want with BUILD_SHARED_LIBS:BOOL=YES
• Adds the SOVERSION property to the library
• Bumps the version to 1.0.2. This is pretty pointless as the version has been released already. The correct thing would be to bump it to 1.0.3 and do a new release.

The bump and source configure prevention I'm not that fussed about. Being able to build shared libraries I would like to be able to do so that I can package up the library correctly and update it through deployment of new packages rather than building in static code to the dependent projects.

[mattyclarkson]

@no1msd, any chance this could get merged? If you have no interest in maintaining the project, would you like any help with maintaining it?

[yurivict]

Just removing STATIC at https://github.com/no1msd/mstch/blob/master/src/CMakeLists.txt#L25 suffices for the build to respect BUILD_SHARED_LIBS.