path -> filepath (for rna and operators, as agreed on with elubie)
path -> data_path (for windowmanager context functions, this was alredy used in many places)
Running scripts directly didnt call the register function, even though this is not essential its good to be able to run a script directly and see changes in the UI.
The 'save over' popup was only appearing based on a string comparison of the operator name ("Save"). Changed this to use a hidden operator property: "check_existing". Python operators must
have this property for the file selector confirmation too.
This property can also be set to false, to prevent checking for existing files, useful in the File->Save menu item to prevent the dangerously missable confirmation popup.
- use xml.sax.saxutils.escape() to give an XML compatible string.
- in some cases material indicies could be invalid. use the default material rather then throwing an error.