Use multi-value %_performance_attributes% ...

... instead of %_performance_live%, etc.

Modifies #285.
Fix layout (zas comments)

Note: Whilst the previous indentation of "and" was incorrect as per
PEP-8, I think it was actually more readable.
Fix layouts again (zas comment)
Merge pull request #302 from Sophist-UK/sophist_enhance_#285

Use multi-value %_performance_attributes% ...