Matrix Slice tests.
Matrix Slice tests.

Still missing some coverage in Matrix.__getitem__(). It's not clear what the inner if statements are catering for.

JElchison/Numberjack,eomahony/Numberjack,JElchison/Numberjack,eomahony/Numberjack,eomahony/Numberjack,eomahony/Numberjack,JElchison/Numberjack,JElchison/Numberjack,JElchison/Numberjack,eomahony/Numberjack