pcbnew: solved: info not displayed when clicking on a module. Removed: gcc 4.2.1 warning in moduleframe.cpp

Comments added in some functions.

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.