20170513_egp-cig-reu

New particle interpolation scheme bilinear least squares
using singular value decomposition algorithm. Currently
only 2D models are supported. We chose a simple overshoot
and undershoot correction scheme, mainly to truncate based
on local cell maximum and minimum property value.
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(Elbridge Gerry Puckett, Ying He, Harsha Lokavarapu 2017/05/13)