bundler -- two enhancements mktemp and re-use target

[Fred T. Hamster]

1) get the bundler to support a mktemp style variable,
so we can get temporary folders that are cleaned up
after the bundle runs (or after its being created for a source
execute style thing?)

2) allow a target to be re-used more than once.
for this we could support a name that's separate from the action to take.
currently only a set of unique action names are supported.
if we could name it like:

TOC...
whack_dir_prior:whack_dir=t
....
whack_dir_after:whack_dir=t

they could each use the action specified more than once, but be unique.