Clean up spatiotemporal Matlab code for publication

[stiber]

• Readme.md can be converted to Contents.m, which Matlab uses in its internal help system.
• Code itself should be made "pretty", which good comments -- i.e., something we'd like someone else to see.
• We should look at its computational complexity. If it really takes 5 days to run, that's OK, but maybe there's something that can be done to take parts of it that are currently interpreted and make them calls to built-in Matlab functions, which would be faster. Let's do a code review when everything is up to see about this.