Vignette row names

[wibeasley]

Thanks for creating this package, @jtilly. I found the documentation very helpful too. I'm just learning the concepts and terminology, so my feelings won't be hurt if you reject this PR.

In the two-sided market section of the vignette, the row names for a utility matrix are Woman 1 ...Woman 3. But if I understand correctly, the rows of the preference matrix represent something different. Are the terms Preference 1...Preference 3 more representative?

The two modifications to the Rmd file are the only real changes I made. The others appear to be the result of how Rcpp auto-generates some code differently.

[coveralls]

Coverage decreased (-0.01%) to 99.54% when pulling b06f8ae on wibeasley:vignette-row-names into 195b87f on jtilly:master.

[jtilly]

Thanks, Will. You're making a good point. We should come up with better row/column names to make clear what's going on. I'm not sure if I like Preference 1, 2, ... We could probably just number the rows instead. While we're at it, we should also change the row/column names of `uM` and `uW` to make clear whose payoffs we're describing.

[wibeasley]

If there's something else you'd like it named, just tell me. It's still set up on my computer.

[jtilly]

Thanks, I already managed to sneak in a little change before I merged.

I'm now going with

##         cols
## rows     Woman 1 Woman 2 Woman 3
##   Rank 1       3       1       3
##   Rank 2       2       3       2
##   Rank 3       1       2       1

[wibeasley]

oh good, I like the brevity of "Rank X" better too.