Addition of make uninstall
Addition of make uninstall

For clean installations, we provide an uninstall command
that will remove all headers and fixed and mapla libraries.

Errors here are ignored, so as to allow for the possibility
of partial uninstallations, which the script will cope with
and continue removing the remaining parts.

cphang99/matrix_playground,cphang99/matrix_playground,cphang99/matrix_playground