Pcbnew, layer manager: add option (popup menu) to always keep copper layers not visible but the active layer, even when the active layer is changed.
Usefull for multilayer ( more than 4 layers) PCBs.
* Make Pcbnew net list dialog honor escape key on Linux.
* Make Pcbnew swap layers dialog honor escape key on Linux.
* Layout and UI policy fixes for Pcbnew swap layer and net list dialogs.
* Layout and UI policy fixes for Eeschema plot dialog.
* Rename fpip.h to fpid.h.
* Fix FPID class compiler errors.
* Restore fpid.cpp to Pcbnew static library source list.
clean duplicate code.
Simplify HPGL dialog: plot offet removed and replace by only one option (plot origin to center of sheet or not)
This is surely enought.