Remove a minor compil warning in shape_collisions.cpp

- Reference is visible on silk and the corresponding assembly layer
- Reference is shown on assembly always on the component insertion point

Hidden references are not forced shown in assembly plots (there is
already a user option for that)

Eeschema: schematic libraries in a sub path of standard libraries paths are now better handled.

Kicad:  more understandable dialog when creating a project from template. Fix also a bug when copying and renaming template files.
Pcbnew: dialog to create new .pretty lib: fix an issue which prevent to open a full disk directory (at least on Windows)

* Create GetNewConfig() and GetKicadConfigPath() to unify configuration file
  creation and location.
* Move Windows configuration out of the registry into configuration files.
* Move Linux configuration files from $HOME to $HOME/.config/kicad to eliminate
  configuration file pollution in the users $HOME folder.
* Fix a bug in the configuration file where the Eeschema hot keys are saved.

Help files: can now be html or pdf files: Kicad search first for a .html help file, and if not found in a path, search for the corresponding .pdf file.
Therefore our .pdf files can be replaced at any time  by .html corresponding files in kicad doc/help sub directories.

eeschema: Find Replace: fix a bug in replace command: sometimes, the string to replace was found, but not replaced if this string contained lower case letters.

Pcbnew: Minor fix in hotkeys. Demos: add an example to use  a local fp-lib-table and local libs, and update schematics and boards.

* Add hot key handled return indicator to DRAW_FRAME::GeneralControl() and
  DRAW_FRAME::OnHotKey() and all classed derived from DRAW_FRAME.
* Add code to all GeneralControl() and OnHotKey() functions to return true if
  hot key was handled.
* Call event skip in DRAW_PANEL::OnKeyEvent() when key event is not handled to
  allow default menu event handler to function properly.

All: Fix crash on close Kicad, when a quasi modal dialog is open, and Kicad is closed from the Kicad project manager.

*  Fix Eeschema back annotation bug where footprint field visibility setting was ignored.
*  Replace two confusing and ambiguous dialogs with a simple single choice dialog.

Pcbnew, Eeschema: release lock file when these editors are closed (Until now, the lock file was released when the full Kicad application was closed, not when the editor was closed).
Should fix Bug #1360470  and Bug #1359502 .

all: fix Bug #1361233 (a template.pro copy file overwrite silently the current project file when a group info is not found, which is a bug, because this group could be just a new group, not yet used)

Eeschema: add dialog libedit options and move options relative to libedit from eeschema options to this dialog.
Ensure some values initialized by the schematic editor and used by libedit are also initialized in libedit even if the schematic editor was not started.
Remove useless commands (save/load project config) in libedit, because now they have no sense.

Eeschema: add dialog libedit options and move options relative to libedit from eeschema options to this dialog.
Ensure some values initialized by the schematic editor and used by libedit are also initialized in libedit even if  the schematic editor was not started.
Remove useless commands (save/load project config) in libedit, because now they have no sense.

.pro file: Settings for schematic editor and library list are now stored in 2 independant sections [schematic_editor] and [eeschema].
This fixes Bug #1360219 (Lost settings in eeschema) and keep separation between code relative to lib management and code relative to preferences.
2 or 3 minor settings could be lost in some designs, but they are very easy to reenter.

* Refresh canvas when user cancels edits so that the discarded sheet is
  cleared from the schematic.
* Add file name validation to the sheet properties dialog to prevent
  illegal file name characters from being entered into the text control.
* Rename FOOTPRINT_NAME_VALIDATOR to FILE_NAME_CHAR_VALIDATOR for clarity.

Rework on env. variable KISYS3DMOD. Until now, was used in different files using different ways, so no consistency between files.
Fix also an incorrect default 3d path read from KISYS3DMOD, when the path was defined without trailing directory separator.
code cleanup.

Rework on env. variable KISYS3DMOD. Until now, was used in different files using different ways, so no consistency between files.
code cleanup.

* Use clockwise and counterclockwise in menu strings which is less ambiguous than + and -.
* Moved the rotate hot key R to the rotate clockwise menu entry string.

* Patch Boost interlocked.hpp from version 1.56.
* Fix segfault in Eeschema when auto save event occurs before root sheet is initialized.
* Add assertion when SCH_SHEET_PATH::BuildSheetList is called with NULL pointer.

* Fix C flag parser when there is more than one flag defined after includes when
   wx-config --cflags is called.