Started refactoring all magnetic codes to use a magnetization vector instead of inc dec
Converted python and cython implementations of prism to new format
Refactored _neprism to use vector magnetization
Finished refactor for gravmag.polyprism to use vector magnetization
Refactored gravmag.sphere to vector magnetization
Mayavi needs to take the norm of a vector magnetization to use as scalar
Updated recipes to use vector magnetization
Updated todo
Made mesher utility funcs take the norm of the physical property before comparing to scalar value
Forgot to add vfilter to last commit
Refactored harvester to use vector magnetization
Merge branch 'mag-refactor' into devel