[RCU] cleaning up old plugins

[Nick Edwards]

Hey All,
 so, over the years we've upgraded major versions, and upgraded and upgraded.
I note we have some plugins we do not use that are circa 2010

Question, if I note all plugins  official in  1.4.9, and any  current
plugins not in the default distro that we still use,   it is safe to
just delete all the rest?

I recall in early days some of these (too long ago to remember which
ones) updated other parts of roundcube, so hoping those have been
replaced by now and it is safe to do so, I think it is from briefly
looking, but thought i'd ask for those more familiar

thanks