pdLabel: drop the need for any StdFont objects

It's a hassle to switch systems now, but I prefer this as it prevents
the creation of unnecessary GDI font objects.  (We create enough font
objects on our own, without VB dual-managing its own copy in the
background!)  This also (slightly) reduces exe size, as we don't have to
store a full StdFont property for each label instance - and given how
many labels there are in the project, this could be non-trivial in the
long run.

I also want to get all pdLabel properties set in stone before expanding
its use to more dialogs, so better to tackle this now rather than later.