PortGroup vs. Portfile search strategy

[René J.V. Bertin]

After-thought: this is of course counter-productive for custom port trees that do not override the main tree but in which you want to use a custom version of an existing PortGroup.

One could think of making an optional check using `getportresourcepath` before scanning over all port trees; the option could be set in sources.conf . Would the existing code require many changes to allow an additional keyword (say `file:///path/to/custom_ports [nosync portgroups_here_first]`)?

R.