Refactor: default iw2d executables path
We set ~/pywit/IW2D/bin
as default path to the IW2D
executables, since this is were the PyWIT
readme suggests to put the executables
We set ~/pywit/IW2D/bin
as default path to the IW2D
executables, since this is were the PyWIT
readme suggests to put the executables