increase MH values for LCZ 7

[matthiasdemuzere]

Suggestion from Alberto Martilli, via email:

Increase the values of MH_URB2D_MIN,MH_URB2D,MH_URB2D_MAX for LCZ 7 of the look up table to
4,5,6 m

instead of

2,3,4m.

This is because the minimum building height that we can assign to BEP-BEM is 5m if we use dz_u=5m (standard value), so there is no point to have a mean building height lower than that. In addition, this will increase the mean street width to 3.33m instead of 2m, which seems more realistic to me,

[matthiasdemuzere]

I agree with this suggestion.

The changes have been made and pushed to branch lcz7_mh.