Move all of the ascii grids out of version control. These are too big. TODO: add code to download and extract these from zipfiles on dropbox. For now, just make sure that local repo has them under ./topo_grids/DM, topo_girds/CM etc
Extract topo variables for iButton locations from the raster::stack objects and avoid storing these as sensors-topo.csv
Modify the pca code and random forest code to use these slightly changed objects (I cleaned out some columns from the sensors and PCA loadings data frames)
Add projection information when reading ascii grids or lat/lon data
sensors-topo.csv