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.

* Derive the pcbnew copper zone and non-copper zone dialog windows from DIAG_SHIM,
  which injects some template code.
* Update UIpolicies.txt to talk about DIALOG_SHIM support.
* Add zone support to eagle_plugin.
* Organize ZONE_CONTAINER class declaration for future privacy and accessors.

 fix a compil warning.
CvPcb: fix regressions :
 Shows now a void field instead of the dummy footprint name $nonane (whenthere is  no footprint selected in netlist).
 The active footprint selection changes only if a new component is selected from the component file,
 and does not change just when the next component is automatically selected, after a footprint selection.
 Speed up delete association and auto associe.