Typo in corollary environment name

[Peiffap]

The corollary environment is currently named mycorr, but should only have one "r". grep reveals about 60 uses of this, I'm currently working on a PR which will increase that number though, so this should be fixed once that PR is merged.

[blegat]

My bad, I was initially making the mistake "corrolary", I fixed it but apparently never renamed the name of the environment