Change multimon/span logic in the rdp file parsing to match the command ...

Change multimon/span logic in the rdp file parsing to match the command line parsing.

New functionality:
- Span will trigger multimon AND fullscreen.
- Multimon alone will also trigger fullscreen.

As a result of this now matching behavior, FreeRPD aligns with the behavior of M$ when opening RDWeb connections. (RDWeb's generated rdp files have multimon set to TRUE, but do not specify any screen geometry, because multimon is supposed to imply fullscreen).