Patch: commandline connect/launch

Attached patch makes it possibe to specify a server description to
auto-connect to on the commandline ("-s mydbserver"), and also to have
pgAdmin automatically launch the query tool ("-s mydbserver -q"). It
will still open the main window as well, as there seems to be
interaction between the query window and the main one that I'm not fully
understanding yet :)

It also rearranges the commandline parsing to use the wx class for
commandline parsing. It just made things much easier to do it that way.
Hopefully I didn't break anything else :-) As a bonus, there is now a
"/h" for help on commandline args.

Thoughts/comments?

//Magnus