FlowTopo 0.1.0

The version archived on Zenodo with the companion paper
(MERIT-FlowTopo code, https://doi.org/10.5281/zenodo.22227621).

Three serial orderings, three parallel layerings, two spatial partitions
and three propagation manners for D8 flow networks, with four kernels
(upstream drainage area, flow length downstream, flow length upstream,
Strahler stream order) cross-checked on the bundled 731 km² example basin
cut from MERIT Hydro. Python 3.10 to 3.12; numba optional, for the threaded
kernels.

The README on main has since been rewritten; the code is unchanged.