Minor fixes. Board and footprint editors: Auto update 3D display after footprint or board edition. Convert gendrill dialog from DialogBlocks to wxFormBuilder

Preparing 3D view autorefresh when editing a footprint in modedit (not yet working)

preparing auto refresh of the 3D view in mod edit (not yet working)

* Closes bug report 570021.
* Removed unused variable from pcbnew.cpp
* Use new message box methods when saving board file.
* Minor code cleaning.

* Removed redundant empty string test, thanks again Alain.
* Minor code cleaning.

* PCBNew remembers last net list read during the current editing session
  as well as between project editing sessions.  Closes bug 576902.
* Separate PCBNew application settings from project file settings and
  allocate them dynamically instead of statically to make it easier to
  eliminate global variables.

Pcbnew: Fixed minor problems (bugs 568357 and 568356). Changed French word COTATION to DIMENSION in class COTATION (now class DIMENSION)

Pcbnew: Fixed minor problems (bugs 568357 and 568356). Changed French word COTATION to DIMENSION in class COTATION (now class DIMENSION)

Pcbnew+Gerbview: Fixed minor bugs and printing problems, and others minor enhancements, from testing branch