In essence we withold application of the :latex filter until we
do html generation.

update dependencies

#14

#14

document tag parameters

Normalize tag parameters using Ruby's OptionParser. This
breaks the API but gives us a standard way of handling
parameters going forward.

This commit also adds optional prefixes used by the
bibliography, cite and reference tags. See #12.

the cited option will limit the bibilography to those entries
which have been previously cited on the same page using the
cite tag.

see #10

#8

New tag to print a formatted citation