Delete closing times from notes
Use org-link face as base of citekey face
Fix inconsistent citekey highlighting

With the previous approach, some citekeys weren't highlighted until text
near them was changed. I'm still not certain why this is, but using
`org-font-lock-hook' seems to fix it.
Expand some NEWS items
Add command to open first citekey heading link
Update copyright date
Prefer current buffer when finding citekey heading

Several functions use `org-find-exact-heading-in-directory' to find the
location of a citekey heading. However, when called with a citekey at
point, it is likely that the citekey is in the current file (assuming
files are arranged by general topics), so first check the current buffer
and, only if it isn't found there, search all Org files in
`bog-notes-directory'.
Put header at top of tests
Add missing require to tests
Add bog-tests--with-temp-text macro