SystemTimeStamp used to be an opaque class, as it was provided by
`system_{linux/other/windows}.h`. Because of this, code dealt in
SystemTimeStamp pointers, and getting the current timestamp required a
memory allocation. Now SystemTimeStamp is just a
`std::chrono::time_point`, we can make the code cleaner and faster by
just directly keeping SystemTimeStamp instead of pointers around.
* targets are now created in top-level build directory
* more things are now configured through CMake options
* changed debug build detection from NDEBUG to DEV_BUILD
* moved po and desktop directories
* moved last unit test out of src directory
* changed win32 implementation to QueryPerformaceTimer system function
* refactored system utils code
* proper tests for time utils and update event creation in application
* should fix issue #134
AbigailBuccaneer