Log message:
zug: add missing catch2 dependency to fix build

Only needed for tests.

Log message:
zug: add version 0.1.1

zug is a C++ library providing `transducers`. Transducers are composable
sequential transformations independent of the source. They are extremely
lightweight, and can be used to express algorithms over pull-based sequences
(iterators, files) but also push based sequences (signals, events, asynchronous
streams) in a generic way.