Added initial Boyle/Coello soiling model#26

Merged

cwhanse merged 4 commits intosandialabs:masterfrom

DanRiley:master

Jun 27, 2019

Commits on Jun 24, 2019

Commits on Jun 25, 2019

Changes to Boyle/Coello soiling model per comments
DanRiley
committed

Commits on Jun 26, 2019

Updated reference for Coello/Boyle soiling model
DanRiley
committed