Add new username format plugins and hyphen separator formats

[strikoder]

Summary

Adds 13 new format plugins to format-plugins.rb, covering two areas:

New dot and initial formats:

• first.l — firstname, dot, last initial (e.g. john.d)
• LastFirst — lastname concatenated with firstname (e.g. DoeJohn)
• Last.First — lastname, dot, firstname (e.g. Doe.John)
• LastF — lastname, first initial (e.g. DoeJ)

Hyphen equivalents for all existing dot-separated formats:

• first-last (e.g. john-doe)
• last-first (e.g. doe-john)
• f-last (e.g. j-doe)
• first-l (e.g. john-d)
• last-f (e.g. doe-j)
• l-first (e.g. d-john)
• Last-First (e.g. Doe-John)
• First-Last (e.g. John-Doe)

Changes

• format-plugins.rb — new plugins added before the =begin block
• README.md — updated --list-formats example output to reflect new plugins