A secondary default path for TagTrees to be used for generating TagTrees from within another TagTree

[novoid]

Note: this feature implementation requires #16 to be implemented before.

I want to be able to generate a secondary TagTree when I'm browsing a existing TagTree.

For example, when I've generated a TagTree for my photographs and I'm within the TagTree directory "cliparts/cars" I want to be able to generate yet another TagTree just for the current files in the "cliparts/cars" directory. This way, I can "filter/browse/navigate" all files that are tagged with "cliparts" and "cars" for all other tags including mutual exclusive tags whose no-tags-directories aren't provided in nested directories.

The new links need to link to the original files and not to the primary TagTree files.

When I do want to generate a TagTree from within the secondary TagTree, I might as well re-use the primary TagTree directory for the third TagTree (alternating use of TagTree directories).

Using that feature requires either a command line option for a different TagTree base directory or another TagTree base directory in the config file from #16.