v0.2.3 plotting functions and field vs model rLA tests

Merge pull request #37 from jread-usgs/master

New function w/ generic rLA methods

v0.2.1 glmtools syntax overhaul

Modified function names and operations, added helper functions, simplified depth-subsampling routines, added package data.

v0.1.5 rGLM

Merge pull request #27 from jread-usgs/master

updated examples to current version of rGLM