This new hierarchy makes it easier to work simultaneously on data and
the script, simplifies deployment to tempdir and makes the launching
script naming consistent with simple.sh.

"doc" (not manpages) is built and installed with others.

Otherwise tests with --prefix break since they operate from independent
folder.

This should be consistent with `ffoom` and `ffdoc`

 *  Instead of cp, use *install*.
 *  Store paths in paths.ini.
 *  Allow arbitrary number of path groups (bin, man, share, libexec...).

I have no idea what I was thinking when I added the pipe there...

Although pretty, this way of initializing ffoo must go since it's
not possible to protect it with a working `|| exit 3` clause.

Problem is that bash will create the pipe no matter if the ffoom call
eventually succeeds or not, so in case ffoom is not ready we end up
sourcing and empty file--which always succeeds.

Use this parameter to prepend directory to module search path.