MigrationVersion compareTo is very slow

[pwielgolaski]

I noticed during profiling our app that migration takes(4s - 4 migrations) quite long and after tracking down I noticed that implementation of MigrationVersion is quite ineffective as it don't cache pattern and use patterns to parse string every time compareTo is called, which is often as you put and get it from Map.

[axelfontaine]

Thanks for submitting the issue and the changes.
I don't know why you are seeing these numbers, but I strongly believe the problem must be somewhere else.

I've merged your pull request anyway as the implementation is simpler than the current one now that alphanumeric versions are no longer allowed (they were in Flyway 1.x)

I've also added you to the hall of fame: http://flywaydb.org/contribute/hallOfFame.html

Cheers
Axel