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.