Updates based on pull request feedback

* Renames `graphviz_catalog` namespaces to `planetarium_catalog`
* Several stylistic changes / better use of existing clojure library
  functions
* Get rid of extraneous input stream reference in tar/gz library
Add a lazy `all-entries` sequence to the tar archive library

Previously, if a caller wanted to loop over all of the available
entries in a tar archive, they'd have to do some fairly nasty
loop/recur stuff.  This commit adds an `all-entries` function,
which returns a lazy sequence of all of the entries in the archive.
This allows callers to write much more idiomatic clojure to iterate
over the entries in the archive.