Minor changes for VBTonto
Min and max residual density and fixed 3d cube file.
Merge branch 'master' of https://github.com/dylan-jayatilaka/tonto into minmax
wrong minmax residual density
Fixed put_minmax_residual_density, purified routines, updated tests
Merge branch 'master' of https://github.com/dylan-jayatilaka/tonto
Merge branch 'master' of https://github.com/dylan-jayatilaka/tonto