OnInit & InitPaths

Hi

The move of some code from OnInit to InitPaths (in pgAppBase)
broke the OSX version, because on OSX we want to add
some directories inside the bundle to the path (To
be able to ship the slony-sql-scripts, and pg_dump
with pgadmin - Currently, it's not added to the bundle,
but I plan to do this).

This would mean that we'd have to add another
plattform-specific conditional to OnInit,
since the path-Variable is only available there.

I therefor suggest that path is made a instance
variable of pgAppBase, and that the path is
prepared in InitPaths. I can come up with a patch,
if no one objects.

greetings, Florian Pflug