Replace getProperty/setProperty keyword parsing

[APanasenco]

• Remove automatic processing of getProperty/setProperty parameters/keywords as class parameters.
• Add attribute(s) that will replace the functionality.

As of now, the keywords passed to getProperty/setProperty are automatically considered to be class properties. I think this is a bad practice because it involves IDLdoc assuming too much about the user's coding practices. I, for one, automate the retrieval of all keywords so that the only thing I have to maintain is three lists: lists of keywords user can get, set loosely, and set strictly (and maybe a translation table). IDLdoc parses my getProperty _extra keyword as a class property. This feature needs to be removed, and either a "property" attribute or "get" and "set" attributes to parameters/keywords need to replace it.