Improving CMake packaging

[jcarpent]

Dear V-HACD developers,

First, thanks for the very nice library.
I would like to improve the overall CMake packaging of V-HACD for easier integration with other libraries.
I notably suggest exporting the targets (header only + applications).

I can handle this change and provide a PR. @jratcliff63367 and other developers: are you interested?

Best,
Justin

CC: @lmontaut