new info method: %running_nested

this allows commands to tell whether they're running as a nested command or not
most useful for tweaking output
if an env assign was evaluating to undef, it was blowing up; fixed
now doing env expansions for nested commands
hopefully very temporary way to make `vc commands` respect the $VCTOOLS_RUNAS var

this is a super-cheesy hack, so hopefully it doesn't have a long shelf-life
first, very basic cut at a Subversion config

this is basically just so anyone with any Subversion repos kicking around won't blow up
it includes some basics, but probably not enough to be truly functional yet