Greatly extended feature set

[charludo]

NEW

• per-project session and shada handling
• autogit option
• shutdown command
• startup & shutdown scripts
• reopen last opened project
• tab completion for paths and scripts

IMPROVED

• no more nested deps; uses luarocks instead!
• complete refactor
• various bug fixes
• much nicer README
• enable highlighting on project reopen

...plus probably a bunch of stuff I'm forgetting about, this is a rather large update.