Adds a --file option that will either:

  - pull the date from a vimwiki filename
  - pull the date from a p1k3 entry path
  - pull the day from file's mtime

Aggregates some stuff by date range.

This is Tyler's bash version, just because it doesn't have much in the
way of dependencies.

firefox-wrapper: start firefox (a workaround for some $PATH nonsense).

edit-clipboard: open current contents of clipboard in $EDITOR, write them
back to clipboard.  relies on xclip.

mcd(): a function to make a path and cd into it.

These were missing a `%`.

This should be slightly more correct and doesn't result in an extra blank
line.

See: https://p1k3.com/2016/7/11/ - "extracting all (?) of the filenames
from packages available in debian"

Amends last commit by tacking on current changes.