autoroute functions: code cleaning

* Use index when saving layers to handle translated layer names.
* Add LOCALE_IO switcher when loading s-expression format.
* Make SEGVIA default to through hole to improve file size.
* Don't save default orientation of 0 degrees in TEXTE_MODULE and TEXTE_PCB.
* Don't save default zone configuration parameters.
* Save multiple zone corners on a single line.
* Fixed missing ( check in graphic and module arc parsers.
* Consistency improvements for DRAWSEGMENT and EDGE_MODULE objects.
* Minor tweaks to D_PAD formatting.

Pcbnew: automatic selection of plugin when loading a file with .kicad_pcb extension from history list.
Very minor other fixes

fix incorrect use of KIROUND instead of KiROUND in parseBoardUnits( const char* aExpected ) (see comments in .h file)
very minor fix in pcb_parser.cpp
Fix scaling issue with nanometers in gpcb footprint import.

* Change save order of drawings to match legacy file format object order.
* Set end point of SEGVIA to start point so the round trip back to legacy
  format is the same.
* Fixed bug saving and loading oval pad drill parameters.
* Fixed bug saving and loading rectangular pad deltas.
* Fixed missing layer for PCB_TARGET.
* Fixed EDA_TEXT italic bug.  Thanks Dick!
* Remove some left over debug logging statements.

Pcbnew: fix issue about order of tracks this order was modified when reading and writing a board, even without any change in board.
Fix compil warnings and wx28 compatibility.
code cleaning in autoroute functions.

* Apply Dick's patch along with a few minor changes to fix some clashes with
  changes in my branch.  Thanks Dick!
* Added missing DRAWSEGMENT line angle.
* Fix thru hole pad layer mask issue.

Some code cleaning in autoroute functions.

Tracks should be loaded in the same order as they were saved, no exceptions.
This is for the version control system user.
But even with this objective now implemented in LEGACY_PLUGIN, the TRACKS
are still going through a food processor after they are loaded, and the poor
version control system user has no relief, even with this patch.

TRACKS are always modified after being loaded, and I think this needs to be fixed still.

* Add s-expression file parser object and keyword files.
* Fix minor issues with s-expression file formatting.
* Fix a minor bug the zone container fill state parsing in the legacy plugin.
* Move EDA_TEXT visibility definition to eda_text.h.
* Add minor BOARD_ITEM object improvements to support s-expression file
  parser.

Minor code cleaning in autoroute files.

fix nanometer compatibility.
minor code and comments cleaning (although theses files need a lot of code cleaning)

fix nanometer compatibility.
minor code and comments cleaning (although theses files need a lot of code cleaning)

pad and via sizes from those settings when diameter is not given
in the local object.  Calculation algorithms are inferred from the
UI help of the Eagle program.

For edge connector type of footprints, some copper pads can be on the
back side even within packages.

Flipping of packages to back was not being done correctly, but I think this 
is working now.

There are still remaining issues with text positioning that I am working on.

Eeschema: Fix incorrect display refresh when editing the reference of a component from the popup menu.

CvPcb: fix  focus issue when the display footprint frame is shown (the footprint list loses the focus each time a new footprint is selected, therefore the keyboard cannot be used to select footprints)

Sketch for BOARD::Move().  Pass page_width and page_height to PLUGIN::Save().

Eeschema, Libedit: Fix bug that can crashes Eeschema: In libedit 2 mandatory fields could be deleted. Fixed now.
Very minor other fixes.