Investigate influences of domain decomposition in the CMake setup

[cilwerner]

Domain decomposition can be changed prior to runtime. Questions to ask are;

• Is default domain composition best option
• How can I specify the domain decomposition before runtime
• Do I need to determine the best layout manually
• What is the option to turn domain decomposition on/off

[JonMcCullough]

Discussion/examples written into Episode 2. TODO - check if Parmetis works on scale of tests available, if not remove from Ep. 2.

[JonMcCullough]

ParMETIS done in latest update - results quite good for this size of domain