support MFDA

[pesekon2]

fix #148

[pesekon2]

I am working on the MFDA support. The work progressed, but now it complains here in cell_runoff() that self.vol_runoff_pre is not defined. It is surely not defined but it is not defined even for D8, so it is not an MFDA-connected issue, but still should be solved.

@jerabekjak: Is it wrong that vol_runoff_pre is not defined? Should it be defined? Where? Or should another variable be used (vol_runoff? vol_runoff_rill?)?

[pesekon2]

@jerabekjak: Now, the computation with a configuration file posted below ends in MaxIterationExceeded. Is there an issue with the computation somewhere, or is it expected behaviour for the following configuration?

[data]
rainfall: tests/data/rainfall.txt
pickle: tests/data/destak.save

[time]
# maximum and initial time [sec]
maxdt: 30
# end time of simulations [min]
endtime: 60

[output]
outdir: tests/data/output
printtimes:

[logging]
level: DEBUG

[processes]
typecomp: rill
mfda: True