Thanks for the PR. If I understand this correctly, you removed the dot at the end of each message, right? That by itself seems reasonable, though the default messages and most of the other translations still use the dot. I wonder if the inconsistency will be more problematic then the current "perentorial" form (I'm not sure what that word means, though, seems like a mix of italian and english?).

The other change is also good, though should also be applied consistently, at least for the other date methods.

What do you think?

You're right, "perentorial" seem not to be an english word. According to google translate I should have said something like "final" or "imperative". Sorry about that.

I agree with you about the consistency concerns. This is why I decided to change make those changes:

• The messages can be changed that way because probably different languages (and therefore cultures) may not intend the final dot in the same way. This is just a matter of "common feeling".
  The problem arises when the plugin is used in a page that is provided in many different languages: in that case the presence of the final dot in some localization and its absence in others could lead to some layout differences. Probably the choice to include it or not depends on the typical use of this plugin.
  Personally I think that having a dot at the end of an error message is not required, since the message itself is not supposed to belong to any complex sentence. For instance in my code I displayed the message in a jqueryui tooltip, and the final dot looked completely out of context (and a bit ugly too).
• The reason of the other change is obvious, and I completely agree with you about the need of a consistent change throughout the code. I just changed that method because I was working with it and noticed the "language inconsistency", so I looked up the code and made the fix. I didn't had the time to go through the other methdos (and to understand the underlying implementation of the plugin to see if there were other places to fix), but still I wanted to share what I did.

Since there were never any complaints about the dot before, I'm not sure if others are fine with them or just changing the messages as needed. I agree that they don't make a lot of sense in those sentence fragments. Also it looks like the date method is the only one with custom implementations in additionals. So I'll go ahead and land your PR as is and update the other two methods to also use the existing message.