Merge remote-tracking branch 'origin/NIFTy_8' into code_formatter

18 jobs for code_formatter in 38 minutes and 32 seconds (queued for 5 seconds)
Name Stage Failure
check_code_formatting Static Checks
     df1 = var0.ptw(func_name).jac(ift.full(lin.domain, 1.))
# rtol depends on how nonlinear the function is
- ift.extra.assert_allclose(df0, df1, rtol=100*eps)
+ ift.extra.assert_allclose(df0, df1, rtol=100 * eps)

Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1