Progressbar: make len optional defaulting to fill all available space

[comigor]

:warning: This is breaking! It changes progressbar argument order

Make len optional and the third arg of progressbar, defaulting to fill all window space.

[metal3d]

Ok as it could break something for those who are using it, I think that I will make a new makor version with that PR later

[metal3d]

Can you please try to resolve the conflict? Thanks a lot

[metal3d]

I made others adaptations. Thanks for your PR, but unfortunately it now doesn't fit the code base.