refs #7200 initial modifications to MDEvent Factory to accept new

 templates from MDFlatBoxTree class
refs #7200 rewritten old workspace factory as workspace metaloop
refs #7200 rewritten existing MDEventFactory using TMD as example
refs #7200 Added MDBox factory to MD events factory
refs #7200 Created proper factory method for MDBoxes/MDGridBoxes
refs #7200 MDBoxFlatTree is not templated class any more --

all code generation moved to MDEventFactory
Merge branch 'feature/7200_MoveFlatTemplatesToMDEventFactory' into develop