new API - first pass groundwork
parameter check functions for new API (and cmdline?)
second pass API changes, first tests
second round of new api fixes + tests
more bits of the new API
add missing internal header file
tests & fixes for cipher/prf iterators
remove outdated comment
work around the usual C++ fun
get rid of unused struct
new API - add back error function; throw in new state change callback
slowly prepare 2.0

 * mainly merging back to master to get it to build again.

 * still need to write some more tests for the new API and the new man
   page.