gerbview: fix an issue when using layer list in toolbar to select layer (back to old layer under Linux)
Refresh screen when active layer is changed from the layer manager.

Gerbview: tweaking code: Now the active layer is drawn on top of other layers. This is an enhancement in stacked draw modes.

others: fix minor issues.

* Remove clearance and net class name read only text boxes from PCBNew
  auxiliary tool bar.
* Display full net class information in message panel when an object that
  supports net classes is selected.
* Move coordinate string conversion function to EDA_DRAW_FRAME object and
  made it more versatile.
* Refresh message panel text when units change.

Pcbnew: dialog plot: make message window resizable, add tool tip and remove unused sizers.

* Move locate function code into schematic screen object.
* Move test for junction needed into schematic screen object.
* Move test for marking connected items into schematic screen object.
* Move delete item function code into schematic screen object.
* Move delete all markers code into schematic screen object.
* Add method for locating multiple items in schematic screen object.
* Fix minor bug in schematic field object hit test declaration.
* Initial encapsulation work on item picker object.
* Remove duplicate doxygen comments from item picker object source file.

All: fix a minor bur annoying issue: incorrect cursor shape after a block command (mainly when a tool is selected)

Pcbnew: Fix a very minor issue in left toolbar. Add option in dialog bloc to move,copy ... items on invisible layers or not.

* Factor change schematic component orientation code out of switch statement
  into separate function.
* Remove redundant command events from schematic editor hot key handler.

* Change EDA_ITEM set flag function to set flag bits using logical or
  instead of assignment.
* Add clear flag function to EDA_ITEM to clear flag bit using inverted
  logical and.
* Factor change schematic text type code out of switch statement into
  a single function call.
* Schematic text orientation function renaming improvements.
* Lots of small coding policy changes to updated files.

All : modify macro FROM_UTF8, to ensure compatibility with files using a non utf8 encoding (old files created under Window, having some non ASCII characters).

* Factor component unit select handling out of huge switch statement into
  a separate function.

* Fix grid select box update bug on context menu.
* Fix via size and track width select box update bugs.
* Fix layer pair indicator button update bug.
* Fix auto track width tool bar control enable bug.
* Fix via size and track width select status bug in context menu.
* Fix layer select box and layer control widget select bug when current
  layer is removed.
* Add virtual function to notify objects derived from EDA_DRAW_FRAME that
  the units setting has changed.
* Coding policy class naming fixes.

Eeschema, Pcbnew: fix minor issues about mouse cursor position, when loading files or entering sheets.

Pcbnew: Better selection of corners and edges in zones. Usefull when selecting edge/corner by right clicking on a zone outline,  for hight density boards.

Pcbnew: dialog copper zone: fix bug 726999. Remove unwanted resizing of dialog frame when selecting options.

Eeschema: bug fix:when clear annotation, delete annotation using current scheet only delete annotation of other sheets.

Use UTF-8 encoding only in kicad files. Under Linux, this was already the case. Under Windows, texts with  non ascii characters must be corrected.
This ensure compatibility between platforms.

* Merge three separate rotate code paths into a single rotate item function.
* Reduce three separate rotate command IDs into a single rotate command ID.
* Move pin rotate code into pin object.

* fix incorrect bounding box size calculation of schematic components.
* fix incorrect bounding box position and size used when schematic components are not found in lib (dummy lib componen used).
Pcbnew:
* Fix issues in block selection for arcs in modedit. Minor code cleaning.
CopyToClipboard: fix incorrect call to PrintPage (bad parameters)