Pcbnew: footprint library table fixes.

* Replace illegal file system characters when reading legacy libraries to
  prevent FPID parsing errors and allow saving to PRETTY file format.
* Create validator to filter illegal file system characters from footprint
  name text edit controls to prevent issues when saving to PRETTY file format.
* Add missing source file licenses and some minor coding policy fixes.

common/string.cpp

@@ -1,3 +1,26 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2004 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
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
 /**
  * @file string.cpp
  * @brief Some useful functions to handle strings.
@@ -5,9 +28,18 @@
 
 #include <fctsys.h>
 #include <macros.h>
+#include <richio.h>                        // StrPrintf
 #include <kicad_string.h>
 
 
+/**
+ * Illegal file name characters used to insure file names will be valid on all supported
+ * platforms.  This is the list of illegal file name characters for Windows which includes
+ * the illegal file name characters for Linux and OSX.
+ */
+static const char illegalFileNameChars[] = "\\/:\"<>|";
+
+
 int ReadDelimitedText( wxString* aDest, const char* aSource )
 {
     std::string utf8;               // utf8 but without escapes and quotes.
@@ -414,3 +446,34 @@ int SplitString( wxString  strToSplit,
 
     return 0;
 }
+
+
+wxString GetIllegalFileNameWxChars()
+{
+    return FROM_UTF8( illegalFileNameChars );
+}
+
+
+bool ReplaceIllegalFileNameChars( std::string* aName )
+{
+    bool              changed = false;
+    std::string       result;
+
+    for( std::string::iterator it = aName->begin();  it != aName->end();  ++it )
+    {
+        if( strchr( illegalFileNameChars, *it ) )
+        {
+            StrPrintf( &result, "%%%02x", *it );
+            changed = true;
+        }
+        else
+        {
+            result += *it;
+        }
+    }
+
+    if( changed )
+        *aName =  result;
+
+    return changed;
+}