fix issue BenMql#25 and issue BenMql#18; rolling quicksaves now optional

fix issue BenMql#24

v1.2.0 Introducing Smagorinsky models

JOSS release

minor fixes (cfl, eqns input, processing routines)

Fields in physical space can be defined using an arbitrary number of …

…z-derivatives (used to be limited to first order)

noise amplitude can be choosen; anisotropic cfl factor if necessary; …

…minor bug fixed (eqn input, NL term of zero-mode eqns)

mean flows can be renormalized; fixed U(rms) on display; removed unus…

…ed .o file from Makefile

interpolate_checkpoints.py now copies dt.sav so that the user no long…

…er needs to copy the file by hand

distributed DFT tests: --checks flag available