pull changes from upstream through commit 1fd6612522d36dc4488b0fc16b893eace9ebaeef.  adds support for 'source' invocation, tom's pwd patch, quell echo spew, and restore pwd (for source invocations).
pull changes from upstream through commit 1fd6612522d36dc4488b0fc16b893eace9ebaeef.  adds support for 'source' invocation, tom's pwd patch, quell echo spew, and restore pwd (for source invocations).

kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1,kongr45gpen/bzflag-import-1