* contrib/make.hbs
+ added installation support of contrib specific public files
(.hbc, .hbs, local headers, .def files, readmes and tests)
* config/global.mk
* set install destination for contrib specific public files to
<root>/contrib for non-*nix and /opt/harbour/contrib for *nix
systems.
* utils/hbmk2/hbmk2.prg
* changed HB_INSTALL_CONTRIB to HB_INSTALL_ADDONS
F.e.:
export HB_INSTALL_ADDONS=/usr/local/share/harbour/contrib:/usr/local/share/harbour/addons