fixed one of the slides
Null Clines code (in R) for the Shrimpy
added the legend
Merge pull request #29 from CarrieRider/Dev

Dev
Merge pull request #30 from TatyaniaM/Dev

Dev
Fixed the null cline graph and added the vector field
Made the vectors larger in the phase plane plot
Merge pull request #30 from KellyBlack/Dev

Dev