Non-root plug-in install.

[rvclayton@acm.org (R. Clayton)]

I tried to install a plug-in (tcl) in firefox (1.0.7) on debian (testing,
upgraded weekly).  The install failed because it tried to write into
/usr/lib/mozilla-firefox/plugins and I wasn't installing as root.  I fixed this
by making the plugins directory writable by group staff.

Is this the best way to avoid plug-in install failures, or is there something
better?  My suspicion is that introducing unexpected files into system
directories will interact badly with upgrading, either by causing the upgrade
to fail due to the unexpected files or by having the unexpected files get wiped
out in the next upgrade.