Remove most of the code, statically link lib into converter program

* The converter program will be able to open old captures, but is itself
  captureable in new renderdoc builds. This isn't a direct conversion
  but should allow a reasonable estimation and is better than nothing.
* NOTE: The resulting converted file will have no thumbnail, and no
  callstacks (if they were present before). As well as more minor things
  like backbuffers no longer appearing identified as backbuffers, some
  markers losing their colours, etc.

Author: baldurk