added some point-wise convenience functions for FemTools

- onElement test for ReferencElement objects
- pointwise getInverseMap for ElementMaps objects
- fixed some bugs in MultilevelProjections
Add core Gauges functionality

This work was in coordination with:
cekees@gmail.com, mwfarthing@gmail.com, asd@hrwallingford.com

LineGauges and LineGauges_phi require that the measured points be on the
mesh.  PointGauges uses interpolation on the finite element mesh.