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Add support for individual string-type params
New miscellaneous distort tool

Certain one-off distorts (e.g. distorts without tunable parameters) are
useful in specific circumstances, but there are far too many to give
each one its own menu entry.  So I've resorted to collecting my
stockpile inside a single "miscellaneous" entry - not my favorite, but
until I can think up a better organizational scheme, at least this will
make them available to end-users.