[gdome]saveDocToMemory

[Tobias Peters <t-peters gmx de>]

gdome_di_saveDocToMemory takes (among other parameters) a char** and
returns a GdomeBoolean.  The return value indicates the success of the
operation.

Proposal:  remove the char** parameter and return char* from the function
instead, since this may also indicate a failed operation.

As far as I can see, this parameter is the only one with "out" semantics
in the core module (apart from the exception tracking parameters), and it
would be nice if it could be eliminated for consistency.

Bye,
  Tobias