Avoids a name clash in celery
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ref #94

/close #53

This enables to generate both AStA-style and FS-style (and in theory
other) protocols.
/close #88

ref #7

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e.g. [todo:who:what]
e.g. [todo;who]

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Categories can be set per protocoltype.
They are specified as another semicolon-separated argument to
[beschluss;…].
Decisions can be search for their category.
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/close #27

/close #16