GTK+ file dialog wildcard improvements.

The GTK+ file dialog is case sensitive however it does support regular
expressions.  Most of the file dialog wildcards are lower case so only
files with the lower case extensions will show up in the file dialog.
This code adds a method to convert file extensions of any case to the
appropriate (sch -> [sS][cC][hH]) regular expression on GTK+ builds so
all file extension case combinations will show up in the file dialog.

A note to developers: make sure to add a file extension when setting
when setting the default file argument.  If you do don't set an
extension, the GTK+ file dialog will happily append the regular
expression as the file extension which is surely not what you want.

There are still a few known places (mostly gerbview) where there are
some complex wildcard code that has not been converted.

Fixes lp:1720542

https://bugs.launchpad.net/kicad/+bug/1720542

bitmap2component/bitmap2cmp_gui.cpp

@@ -2,7 +2,7 @@
  * This program source code file is part of KICAD, a free EDA CAD application.
  *
  * Copyright (C) 1992-2010 jean-pierre.charras
- * Copyright (C) 1992-2015 Kicad Developers, see change_log.txt for contributors.
+ * Copyright (C) 1992-2017 Kicad Developers, see change_log.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -482,9 +482,8 @@ void BM2CMP_FRAME::OnExportLogo()
     if( path.IsEmpty() || !wxDirExists(path) )
         path = ::wxGetCwd();
 
-    wxFileDialog fileDlg( this, _( "Create a logo file" ),
-                          path, wxEmptyString,
-                          wxGetTranslation( PageLayoutDescrFileWildcard ),
+    wxFileDialog fileDlg( this, _( "Create Logo File" ), path, wxEmptyString,
+                          PageLayoutDescrFileWildcard(),
                           wxFD_SAVE | wxFD_OVERWRITE_PROMPT );
     int          diag = fileDlg.ShowModal();
 
@@ -519,9 +518,9 @@ void BM2CMP_FRAME::OnExportPostScript()
     if( path.IsEmpty() || !wxDirExists( path ) )
         path = ::wxGetCwd();
 
-    wxFileDialog fileDlg( this, _( "Create a Postscript file" ),
+    wxFileDialog fileDlg( this, _( "Create Postscript File" ),
                           path, wxEmptyString,
-                          wxGetTranslation( PSFileWildcard ),
+                          PSFileWildcard(),
                           wxFD_SAVE | wxFD_OVERWRITE_PROMPT );
 
     int          diag = fileDlg.ShowModal();
@@ -557,9 +556,9 @@ void BM2CMP_FRAME::OnExportEeschema()
     if( path.IsEmpty() || !wxDirExists(path) )
         path = ::wxGetCwd();
 
-    wxFileDialog fileDlg( this, _( "Create a component library file for Eeschema" ),
+    wxFileDialog fileDlg( this, _( "Create Symbol Library" ),
                           path, wxEmptyString,
-                          wxGetTranslation( SchematicLibraryFileWildcard ),
+                          SchematicLibraryFileWildcard(),
                           wxFD_SAVE | wxFD_OVERWRITE_PROMPT );
 
     int          diag = fileDlg.ShowModal();
@@ -594,9 +593,9 @@ void BM2CMP_FRAME::OnExportPcbnew()
     if( path.IsEmpty() || !wxDirExists( path ) )
         path = m_mruPath;
 
-    wxFileDialog fileDlg( this, _( "Create a footprint file for Pcbnew" ),
+    wxFileDialog fileDlg( this, _( "Create Footprint Library" ),
                           path, wxEmptyString,
-                          wxGetTranslation( KiCadFootprintLibFileWildcard ),
+                          KiCadFootprintLibFileWildcard(),
                           wxFD_SAVE | wxFD_OVERWRITE_PROMPT );
 
     int          diag = fileDlg.ShowModal();