Modedit: add dialog to edit footprint body items. Fix also minor issues about footprint body items edition.

the millimeters. The attacched patch fixes this and also the comments 
on the generated file to have "Unit = mm" instead of Inches.

CvPcb: serious code cleaning. More comments. Remove useless files and some files renamed with a better name.

Pcbnew: Added: modview. This footprint viewer frame which has the same purpose as Viewlib in Eeschema.
this viewer is built using the new  FOOTPRINT_VIEWER_FRAME class.

    bool g_Zone_45_Only, is now in BOARD::m_zoneSettings.m_Zone_45_Only
    ZONE_SETTINGS g_Zone_Default_Setting is now in BOARD::m_zoneSettings
  * Changed classs ZONE_SETTING to class ZONE_SETTINGS.
  * Changed ZONE_SETTINGS::Import() to operator << ( ZONE_CONTAINER )
  * Added BOARD::{Get,Set}ZoneSettings().
  * Added PCB_BASE_FRAME::{Get,Set}ZoneSettings().
  * Save/load BOARD::m_zoneSettings.m_Zone_45_Only to/from BOARD file.
  * Removed PCB_EDIT_FRAME::InstallDialogNonCopperZonesEditor() in favor of
    ::InvokeNonCopperZonesEditor() declared in zones.h
  * Added ::InvokeCopperZonesEditor() declared in zones.h
  * Removed dialog_copper_zones.h since DIALOG class is now declared in *.cpp.
  * Renamed to enum ZONE_EDIT_T in zones.h
  * SetVisibleAlls() is not called as it was in two previous cases for several
    reasons.  BOARD_DESIGN_SETTINGS constructor controls what is visible initially.
    and in the near future so will the *.brd file.  I believe the user should
    have visibility setting rentention accross editing sessions of zones,
    fields, etc.
  * BOARD_DESIGN_SETTINGS constructor initializes hidden text as not visible.
  * Added PCB_EDIT_FRAME::SyncRenderStates() and PCB_LAYER_WIDGET::syncRenderStates()
    so the checkboxes can be set after loading a BOARD file containing previous
    visibility settings.

Pcbnew: Fix incorrect behavior of undo/redo command (this issue happens only when a new track is created, and an old redundant track is deleted)
Minor code cleaning

  -wxSize         g_ModuleTextSize;      /* Default footprint texts size */
  -int            g_ModuleSegmentWidth;
  -int            g_ModuleTextWidth;

and add similarly named variables to BOARD_DESIGN_SETTINGS, which are 
in a BOARD.

Also commit updated icnos from Fabrizio.

support new zone field ZPriority in kicad_plugin.cpp, enhance TESTLINE() so it does not match substrings

Pcbnew: added a priority level for zones: a zone with a hight priority can be now inside an other low priority zone.
useful for complex zones.
fix in footprint copy.
minor enhancement in netlist/ Footprints Test.

Pcbnew: minor code change in netlist functions.

Pcbnew:  First draft to use a new netlist format ( containing the same info as the intermediate netlist, but using S expressions)
* Eeschema can generate this netlist format.
*   Pcbnew can use (automatic identification) the current format or the new format.
*   Cvpcb does not use yet the new format.