* 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.

Kicad: bug fix: in zip project command: filenames are now quoted in command string. Previously if files have space or other exotic character in name, zip fails.

Pcbnew, Module Editor: fix bug 707692 and other potential crashes (when having a block command in progress and try to make an edit command)

This was due to a duplicate constants ( with sligtly different values)  used to select items in some seach functions that broke filtering. Old definitions removed.

* Boost container release method clobbering sheet pointers causing
  seg faults.

* Use Boost pointer container for sheet hierarchy object.
* Add test for modification in sheet hierarchy list object.
* Add method to clear modification flag in sheet hierarchy list object.
* Improve Doxygen comments for sheet hierarchy list object.
* Remove redundant definitions in prototypes header file.

* Move schematic wire and bus break code into schematic screen object.
* Move schematic test for dangling ends into schematic screen object.
* Remove left over debugging output in schematic screen object.
* Remove unused file eeschema/cleanup.cpp.
* Fix bug in schematic line object hit test algorithm.
* Fix a string concatenation compile error added in r2752.
* Rename class WinEDA_BasicFrame to EDA_BASE_FRAME.
* Rename class WinEDA_DrawFrame to EDA_DRAW_FRAME.
* Rename class WinEDA_DrawPanel to EDA_DRAW_PANEL.

Minor others fixes and enhancements

Pcbnew: bug fix: m_ZoneMinThickness parameter not copied in zone copy function. In copy block, copied zones have an erroneous m_ZoneMinThickness parmeter value.

* Encapsulate file name member of base screen object.
* Encapsulate associated screen member of schematic sheet object.
* Create add screen method to schematic sheet object to simplify setting
  the associated screen.
* Move the change file name code in the schematic sheet object to the edit
  sheet method in the schematic editor frame object to eliminate message
  dialogs.
* Improve reference counting in schematic screen object.
* Add helper type definitions for changing schematic object storage to C++
  containers.

Other minor fixes

  * TokenList2DsnLexer.cmake now supports comments, which start with a leading
    # character, and may be either on their own line or on a line after a token.
  * DSNLEXER::PopReader() now pops even the last LINE_READER* and returns it.
++pcbnew:
  * SPECCTRA_DB now inherits from new class SPECCTRA_LEXER, which led to a great
    deal of simplification and code factoring.
  * Moved specctra keywords into specctra.keywords.

Eeschem: fix bug when moving fields in schematic: incorrect field move for rotated+mirrored components
(added InverseTransform( ) in TRANSFORM class)

Modedit: fix issues when printing a footprint. But needs refinement. Work in progress (mainly "Fit in page" is not working).
Minor code cleaning

  * TokenList2DsnLexer.cmake now wraps each token enum in its own namespace. It
    also no longer setup of the "using" directive in the header file, which was
    bad behavior.  C++ enum values will have name collisions unless the enums
    themselves are different namespaces.
++new:
  * Sweet library is now a DSO/DLL.
  * Brought in SWIG to do a wrap of the Sweet DSO/DLL for unit testing
    and scripting.  The SWIG DSO/DLLs are built separate from the Sweet DSO/DLL
    and are also optional.