Zones not attached to a net are now allowed. Not sure it is a good idea, but a lot of users want this.

(scale now allowed from 0.01 to 100)

Integrate wxFileHistory, add missing header files to fix Linux build, initial search path work, and general housekeeping.

Many stubs are removed but they are connected to a zone.

Pcbnew: force scale 1 in gerber format, regardless the options value. Solved a bug when retrieving plot scale options

eeschema: code cleaning, comments added, and the true number of sheets and sheets numbers in complex hierarchies