Updated `libsimbol.sh': allow `ssh.conf' selection

This is almost never required, except in certain networks that are
complicated enough that a single `ssh.conf' will not suffice.  For
this reason, it has not been added as a shflags option - to minimize
code change.
Updated `libsimbol.sh': speed-up mod/fn resolution

Where the full function name is provided, don't run through the code
completion loop.