Use complete file name as a stem of rc.local temp file.
When cleaning fstab, remove *all* tmpfs mountpoints matching */fah.

This is to support switching installation from one user to another.
Rework langouste3.conf creation -- convert configuration if such exists.

This is to support migration of installation from one user to another.
Previously, langouste3.conf would only be generated if it didn't exist.

Employ a bit smarter approach if the file already exists -- only change
user= and listen_port=.