Eeschema: fixed a bug that crashes Eeschema when the library editor or/and the lib viewer is opened and if the schematic (or an other) is reloaded (that involves libraries are deleted and reloaded)

    Renamed dialog_layers_setup* files.
    Got rid of the header file since there was only one file including it.

* Replace EESchema sheet properties dialog with wxFormBuilder version.
* Editing an existing sheet now marks schematic as modified.
* Code style updates for some of my previous work.
* Improvements to the CMP_LIB_ENTRY object.
* Replaced symbol edit export fprintf code with wxFFile implementation.
* GCC compiler warning fix in pcbnew/drc.cpp.

pcbnew: fixed in dialog_layers_setup2: new number of layers not taken in account when selected only by the copper layers choice list.

    Finished the Layer Setup Dialog.  I assumed that the new layer order will
    be in place soon.  It works fine now, but the layer order is probably
    misleading, since it does not reflect the current stackup but rather the
    future stackup.  I dropped support for a single layer board. The minimum
    is two copper layers.  Avoid the side you don't want anything on.

    Within a month I should have the layer visibility and selection widget
    in place.

    constructor takes a keyword table, so it can be used for arbitrary DSN
    syntax files of your own chosing.  Simply create an enum {} with all your
    unique tokens in it.  Then create a KEYWORD table.  See SPECCTRA_DB::keywords[].
    The reason you want an enum is to give the C++ debugger better type information
    so it can show symbolic integer symbols.
  * Factored out common richio.cpp and richio.h
    which is what DSNLEXER uses.
  * Fixed some minor issues with reading circuit descriptor from a *.dsn file.

  * Moved ReturnLayerName() to static BOARD::GetDefaultLayerName() and migrated
    to a Specctra DSN compatible default layer naming scheme:
        Component becomes Front, Copper becomes Back.
  * set_color.h: Cmp becomes Front, Cu becomes Back.
  * D_PAD::DisplayInfo() changed to use actual copper layer names.
  * more layer setup dialog work, moved all programmatic wxControl instantiation
    into the wxFormbuilder environment, but this is fraught with danger:
    wxFlexGridSizer used the tallest control to establish the row heights, so
    be careful about changing control borders in the scroll panel. The vertical
    size can explode since just a couple of pixels times the number of rows
    is substantial.  Currently I am setting a 5 pixel border only left, top, and right
    but not bottom.
  * Set copper layer count is back in place as a hack until I can get the enabled
    layer bit map fully operational.

fixed redundant hot keys in Eeschema