Fixed issue #73

Escape text type properties in icalendar as recommended in the RFC. Tested on Thunderbird's Lightning calendar plugin: this plugin correctly unescapes the content. Should work for other calendar tools as well.
True. The only point of "static" here is to declare that the method does not depend on object state. A non-static method is a bit like a method that declares a global variable: I would rather avoid it if I don't have a specific use for this additional access. Since "static" (as opposed to global variables) modifies the API, a conceivable future use would also justify non-static methods (you don't want to make a public method non-static later when you change the implementation slightly).

I agree that "public" would be appropriate here too; luckily we probably won't need icalendar escaping anywhere else ;-)