Local resource paths

The idea of the pr is to make it easier to put Factor in a read-only system directory by splitting resource-path into site-resource-path and user-resource-path. Then the boot images can be written to the directory ~/.factor which from a Unix perspective is much saner than the same directory as the binary executable. The pr can be applied as it is I think. In the future it would be nice to also put factor.image in ~/.factor, but that is a bigger job.