SublimeText 2 Gen: Set the sublimeclang_options_script property.

The sublimeclang_options_script property is now set in the project
file. It is set to execute a python script that reads the JSON options
file to get options per source file. Python must be installed and in the
path for this feature to work from Sublime Text.

Source/cmExtraSublimeTextGenerator.h

@@ -48,6 +48,7 @@ private:
 
   void CreateNewProjectFile(const std::vector<cmLocalGenerator*>& lgs,
                                 const std::string& filename);
+  void WriteSublimeClangOptionsScript(const std::string& filename);
   void WriteSublimeClangOptionsFile(const MapSourceFileFlags& sourceFileFlags,
                                     const std::string& filename);
   /** Appends all targets as build systems to the project file and get all