Fixed minor bug in protodisk.py

[ErwanH29]

In amuse/src/amuse/ext/protodisk.py variables were still mapped to outdated names.
Also modified error messages and removed unused libraries from the import line.

[rieder]

Currently you have entirely removed the error messages, was that intentional? I'd like to keep them while both old and new style keywords are accepted.

[ErwanH29]

Keeping them is fine if that is preferred. I am not familiar with the standard.
I only changed it because when I first encountered the bug, I didn’t fully understand the error until I looked into the source code. The new variables have default values, so prompting the function with old variable names will automatically invoke the various ValueError messages.
It seemed easier to remove the error message, warn the user of the deprecated variables, and just directly map the old variables to the new ones. That, or removing the old variable names completely.