Cvpcb: code cleaning.

* Remove global key press variable.  The key press is know passed to
  GeneralControl().
* Removed unused old mouse buttons global variable.

* CVPcb now uses wxUpdateUIEvent instead of set toolbars.
* Removed duplicate event handlers in CVPcb that were factored into
  EDA_DRAW_FRAME.
* Fix definition of GeneralControle() in CVPcb that prevented it from being
  called.
* Remove rarely used and scary refresh code GeneralControle() method in all
  main frame windows.
* Factor zoom menu and tool bar command IDs down to EDA_DRAW_FRAME.

* Old control state handling code completely removed in all applications.
* Factor common control state handlers into EDA_DRAW_FRAME.
* Replaced EDA_ITEM test for newness with IsNew() method.
* Factor vertical right toolbar command handlers out of giant edit command
  switch statement in EESchema and PCBNew.

Tune pcbnew plot dialog. Make actual plotting code independent of dialog widgets and get settings from PCB_PLOT_PARAMS instead.

Pcbnew: dialog plot: use full available height to display layers list.

Pcbnew: remove duplicate definitions of some flags (like EDIT and IN_EDIT) that have exactly the same meaning, but different values... (very dangerous)
Remove obsolete code.

* Rename all member variables and methods that reference the cross hair
  code in draw panel object from cursor to cross hair to eliminate confusion
  between the two concepts.
* Rename cursor capture call backs in draw panel object to improve code
  readability.
* Create helper class for turning off the cross hair while drawing.
* Remove redundant block clear code.
* Remove redundant mouse capture call back reset code when end capture
  call back is called.
* Remove unused function definitions in base draw frame object.
* Lots of minor coding policy and doxygen comment fixes.

* Fix rendering bug in GerbView caused by wxDC scaling change caused by
  setting the wxDC clipping region.
* Eliminate the need to have optional background erasing as the change
  above fixed that problem as well.
* Default cursor handling improvements.

Change in CvPcb: CvPcb does not use now .dcm files, only .mod files  to read modules keywords and doc

* Remove base screen methods from draw frame object and correct current
  screen methods in derived objects.
* Move restore old wires function code into schematic screen object.
* Make add junction method use current screen position instead of store
  position.
* Move poly line ghosting function into the delete current segment method
  as that was the only place is was being used.
* Add method to base schematic object of testing if object has a label
  that can be incremented.
* Simplified the schematic hierarchy traversing code.
* PCBNew Doxygen warning fixes.

* Changed managed cursor callback definition to include the current
  cursor drawing position.
* Modified all managed cursor callbacks to match new definition.
* Added snap to grid option to base drawing frame object.
* Changed add no connect managed cursor callback to use new position
  parameter instead of the stored one.
* Lots of coding policy fixes.

* Remove unused member variable m_SizeVisu from base screen object.
* Move nearest grid position code into base screen object.
* Add get cursor position method to base screen object.
* Add position parameter to OnHotKey method in base draw frame and all
  derived objects.
* Pass logical position on left mouse button click and double click
  events instead of device position.
* Pass logical position to on right mouse button click instead of device
  position.
* Use logical event position parameter for locating items in EESchema
  instead of the stored position.
* Remove unused position parameter when displaying component edit dialog
  in EESchema.
* Comment out debugging macro in eeschema/template_field_names.cpp that was
  preventing debug builds using wxWidgets 2.8.x.

  * macros.h now has TO_UTF8() and FROM_UTF8() which are working converters
    to and from UTF-8 encoding for any wxWidgets build mode.  We can switch to
    them at any time.  I am using them now for specctra conversions and
    elsewhere where I wanted gauranteed UTF8 encoding.
  * added OUTPUTFORMATTER::Quoted( const wxString& ) to simplify converting
    to UTF8 encoded s-expression atoms.  The recommended technique is now simply:
        out->Quoted( wxString ).c_str()

* ActiveScreen global variable is gone, yeah!
* Use drawing coordinates instead of screen coordinates when calling
  GeneralControle().

* Use wxDC to calculate screen center position.
* Minor grid drawing optimization.
* Remove an unnecessary use of global variable ActiveScreen.
* Doxygen warning fixes.

* Remove all occurrences if #ifdef USE_WX_ZOOM and all associated code within
  the #else/#endif block ( old zoom code ).
* Removed the build option for USE_WX_ZOOM from CMakeList.txt and config.h.in.
* Removed all scaling code in base screen object.
* Fixed buffered paint and buffered client DC on Windows.  Buffering works
  properly on Linux and Windows.
* Modified kicad_device_context.h to automatically uses buffering on platforms
  where double buffering is supported natively.
* Remove all of the scaled versions of the drawing functions in gr_basic.cpp
  and any support code.
* Removed all traces of ActiveScreen global variable from eeschema and
  gerbview.
* Renamed Recadre_Trace to RedrawScreen in draw frame object.
* Renamed PostDirtyRect to RefreshDrawingRect in draw panel object.
* Lots of code cleaning an Doxygen comment improvements.

  * DSNLEXER::NextTok() now uses two separate modes to parse quoted strings.
    This gives us the freedom to control our own destiny separate from the
    constraints put on us by the Specctra DSN spec.
  * Added Documentation/s-expressions.txt to explain all this.
  * Enhanced our quoting protocol by moving away from doubling up double quotes
    to a C line escape mechanism.
  * Now support multi-line strings, which when properly escaped, can still be
    read in as a token originating on a single line.