Fix testing bugs listed in 312

[Kmacneil0102]

Fixes issues found in #312.

• Fix bug where an upper case letter was causing errors using Deep Learning on Windows
• Fix bug where the lack of a current result was causing the displacement chart to crash when adding points
• Fix issue where the registration evaluation collapsible button had no contents in the overview step when clicking it
• Improved the "Rock" effect in the results plugin for consistency when using
• Fix the handling of multiple cover prostates, rejecting the first if a second is received

[che85]

Thanks. Looks good to me. I just tested locally.

Having those special situations though with second CoverTemplate/CoverProstate makes this whole thing really complicated.