[Developers] Plone cleanup

[Arni Magnusson]

While squeezing the new 'Libraries' into the 'Community' Plone section of 
admb-project.org, I did some spring cleaning.

The situation was worst in the 'Documentation' section, where I eliminated 
some redundancies and created subdirectories. I hope I didn't step on 
anyone's toes, but you may want to check that. I think some of the links 
still point to non-existing nodes, but Plone seems to be pretty smart at 
finding the intended target in the new location. The 'images' directory is 
still duplicated in two locations.

As before, there are some instructions in the 'Documentation' section that 
could be updated and improved. That should be easier to approach, now that 
the flotsam has been compartmentalized.

Arni