API: Deprecate generatexml of modules revisions/deletedrevisions/parse

API: Deprecate generatexml of modules revisions/deletedrevisions/parse

Deprecate 'generatexml=' by adding 'prop=parsetree' to revisions,
deletedrevisions and action=parse.
'generatexml' of action=expandtemplates is already deprecated and
replaced by 'prop=parsetree'.

Reason: Api parameter to control the output of a module usually gets
added as type to prop=, not added as new parameter. New parameter
usually used as input parameter for the module.

For revisions and deletedrevisions this allows to get the parsetree
without getting the whole content (makes the result smaller, when just
one is needed)

Change-Id: I7403110d7bd07e9eb2a10e1b398d97f0f40298be