Issue tracker tracker: Ghost'd

Currently using ~Ghost'd to track all issues/PRs "by @ghost" (author deleted their acc.)—at Spike's request, that includes those which have been identified.

@anishvundela:

• #1658

@jjfmz42015:

• #2196

@thecoreyburton:

• #711

@twarnercool2:

• #575

Unidentified:

• TODO

Potential sources for usernames:

• mentions from other users (esp. via email)
• Internet Archive
• IRC logs