[python] Make gdb.search_memory accept keyword arguments.

[Tom Tromey]

>>>>> "Thiago" == Thiago Jung Bauermann <bauerman@br.ibm.com> writes:

Thiago> For functions which take more than one optional argument, I enabled
Thiago> keyword syntax which provides a way to specify some optional arguments
Thiago> while skipping others. For instance, you can say:
Thiago> gdb.some_function ('foo', bar = 1, baz = 2)

The memory searching stuff needs documentation.  I intend to be a nag
about this from now on :-)

And if you add keywords to other modules, please make sure to update
the corresponding docs.

Tom