General usability, indexing, persistence, and initialization improvements

[Lambeaux]

General improvement ideas

• Make indexes composite so you can build an index from multiple EDN files
• Write to an "osgeyes" directory in tmp instead of in tmp directly; might need to account for multiple instances of the osg-eyes process running at once, in which case the directory can be UUID-qualified.
• Detect files in ZIP for auto complete (absolute paths?) to make initialization easier; take it a step further with additional, custom REPL initialization steps.