Add ascii.io script to `bin/`

ascii.io is screen recording for the command line. Pretty nifty, yo.
Adds _v command to `bin/`

_v is like cat, except it uses vim to perform syntax highlighting, so
it's like a prettier cat.
Enable interactive comments in zsh

This way I can `# comment` in the REPL. Useful for ascii.io recordings.
Make less use -R by default

This lets colors work in less
Adds treel alias: `tree | less`
Renumber tmux windows when they get closed

This makes sure that there aren't any gaps in the numbering.
Break up zshrc into submodules

My zshrc was getting really long. Now everything is in tiny modules, and
I don't feel so claustrophobic anymore.