Moved clipper to a libraries folder.
Added a DO_NOT_CHANGE_THESE files, nothing developers that the sources in this
folder, is not to be changed directly in this repository, but should rather be
modified in their respective repositories.
Updated the Makefile to build this library.
Updated the Makefile to include the libs folder, as a isystem include
    I.e. do not throw errors, warnings, ect. from these headers.
Updated intpoint, and polygon to include clipper via. compiler lookup.