Minor code cleaning.

* Handle different item global deletions correctly.  No more removing of text
  if graphics is selected.
* Layer settings are always obeyed for modules, zones, text, and graphics.
* Text will be removed from copper layers if all layers are selected or
  according to the current layer.
* Added check boxes for "normal" and "locked" footprints to be consistent
  with the naming for the track deletion options.

Commit patch about  cvpcb, pcbnew and layout editor menu items, with 3 menu labels modified in Eeschema.

EDIT_POINTs show up when there is only one item selected (now after deselection as well).

Selection clearing is invoked using TOOL_ACTION object rather than its name.

Fix also other very minor issues.
Realistic mode shows or not the copper thickness (depending on selected option in preferences) to speed up the screen redraw.

Fix for bug #1285878, build fails with clean repository and high parallelism due missing dependance between router and pcbcommon

TOOL_EVENT message is supposed to contain string as parameter.
Added missing header for class_drawsegment.h (KiROUND).
Renamed SELECTION_TOOL::containsSelected() to SELECTION_TOOL::selectionContains().

[MacOSX] Avoid race between cmake -E copy_directory, which triggers a build error when using an high parallelism

* fp_lib_table.cpp: fix an issue on Windows in ConvertFromLegacy: sometimes, because the comparison was case sensitive, lib nicknames  were not found, although  libs exist ( for instance if a path was given like f:\mypath instead of F:\mypath)
* getpart.cpp: fix a potential bug on a translatable string with has requirements in spelling.
* fix bug  #1066179
* kicad: fix erroneous labels in sub menus.

Removed a few RecacheAllItems() calls, some of them changed to specific type recaching (using TYPE_COLLECTOR & VIEW_ITEM::ViewUpdate() ).
Removed OPENGL_GAL::SetStrokeColor().

Renamed BOARD_CONNECTED_ITEM::SetNet() -> SetNetCode()
Added BOARD_CONNECTED_ITEM::GetNet() for accessing NETINFO_ITEM* of a given item.
Fixed module editor crash when launched to edit a module from a PCB.
Replaced some BOARD::FindNet( item->GetNet() ) calls with BOARD_CONNECTED_ITEM::GetNet().

Renamed BOARD_CONNECTED_ITEM::SetNet() -> SetNetCode()
Added BOARD_CONNECTED_ITEM::GetNet() for accessing NETINFO_ITEM* of a given item.
Fixed module editor crash when launched to edit a module from a PCB.
Replaced some BOARD::FindNet( item->GetNet() ) calls with BOARD_CONNECTED_ITEM::GetNet().

Viewlib: ensure in wxListBoxes  the lib and the component are always shown as selected when a lib and component are specified (when called by the get component dialog for instance)

Fixed a missing group clearing and update for restored VIEW_ITEMs.Fixed a missing group clearing and update for restored VIEW_ITEMs.

Eeschema:  * Preselect the currently chosen component in the browser when pressing the thumbnail view.
* Various smallish documentation updates in the component chooser area.