Add additional sighting flags

[Adam Winer]

... for places that use (H) but don't use SightingFlags.

(Or just use SightingFlags more consistently?)

That's HtmlOutput.writeSpeciesList() and BaseTaxonBrowserPanel.convertValueToText()

Also, consider using (†) for "dead", since that's compact and meaningful.

[Adam Winer]

Resolves Issue #386, Add additional sighting flags (by unifying two stray bits of code on SightingFlags)

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