modflow-obs

fix(Log10 flows and baseflow observation naming): append '-log10' to existing observation name prefix (get_log10_observations); for baseflow observations, replace the second, variable part of the observation name prefix (if any), with '-baseflow'; so that subsequent processing of these observations (into time period statistics, for example) results in unique observation names.

docs: fixes to obs.py docstrings

fix(Displacement observations: sort index before slicing on displacement reference date, to avoid pandas non-monotonic index error