Sanity checks plugin for checking installation path's

[Auke Kok]

Can all the devs please add this plugin to their system and test it?

It will help to reduce common packaging errors where files end up 
outside of the normal locations. It will spot also a few things that are 
not relevant just yet (bin - usr/bin stuff) but it's good for devs to 
start looking at that at this time.

A few of the path tests are warnings you can skip over, the rest are all 
considered an error and will break the compile/install.

Auke