Extending wxFont API & OSX Core Text Implementation (#877)

* Switch to pure Core Text Implementation, Start extended Font API

* mac fixes

* First msw implementation

* Fixing paste error

* fixing typo

* Rearranging lines to former fallthrough order

* Blind fixes for covering new abstract methods

* Blind gtk implementations

* Fixing according to travis ..

* Removing method defined in base

* formatting adaptions

* Extending the schema definition for new weights

* fixing typo, using wxRound, other fixes according to comments

* changes according to suggestions

* fixing init order, before the init of m_info was overridden by Init()

* redo

* redo

* redo

* Cleanup

Removing obsolete code snippets, proper traces for font names

* Moving common code

Only the Get/SetNumericWeight calls should now be implemented in the native part, the ‚old‘ Get/SetWeight are common code and use the numeric counterparts.

* Updating docs

* commit wa missing changes.txt

* Doc fixes

* Full stops added

misc/schema/xrc_schema.rnc

@@ -456,7 +456,9 @@ t_bitmap     = t_url?,
 t_font       = (
                    [xrc:p="o"] element size         {_, t_integer }* &
                    [xrc:p="o"] element style        {_, ("normal" | "italic" | "slant") }* &
-                   [xrc:p="o"] element weight       {_, ("normal" | "bold" | "light") }* &
+                   [xrc:p="o"] element weight       {_, ("normal" | "thin" | "extralight" | "light" | 
+                                                         "medium" | "semibold" | "bold" | "extrabold" | 
+                                                         "heavy" | "extraheavy") }* &
                    [xrc:p="o"] element family       {_, ("roman" | "script" | "decorative" | "swiss" |
                                                          "modern" | "teletype") }* &
                    [xrc:p="o"] element underlined   {_, t_bool }* &