Fixed install problems.

    Esdl now defaults to install in /ERLROOTDIR/addons/esdl-VSN/
    but you can use  'make install INSTALL_DIR=/whatever'
    This requires you to use erl +S1 -pa /INSTALLED_PATH/ when you want
    to use esdl with erlang or you can use ERL_LIBS environment variable.

    Also included is a new glu:triangulate/2 function stolen from wings.
    Build Cleanup by Olivier Girondel <olivier@biniou.info>