Bring cmake build up to parity with autotools and add documentation

[jamiesnape]

This refactors and enhances the cmake build to add missing targets for documentation and the test suite. It also adds the missing documentation for the cmake build, adds the necessary macros for exporting functions for building shared libraries on Windows using cmake, and adds exported targets and config files for ease of use of libccd in other cmake builds.

[jamiesnape]

I added a CMake build to .travis.yml so there is CI coverage of this PR.

[jslee02]

I have a suggestion on configuring CMake config file and version file for libccd. CMake provides a helper function that can automatically generate those files. Using the function would be less buggy rather than maintaining the manual files manually.

[jamiesnape]

Sure, if you prefer. I always deliberately avoid that function, but I can make the change.

[jslee02]

Oh, I thought it's the recommended way by CMake. If this is a matter of preference then I think it should be determined by @danfis but not me. Thanks for the consideration, though.

[mamoll]

👍 I'm not a libccd developer, but do use it in other cmake-based projects.

[danfis]

Merged, thanks guys.