Formatters for Israeli numbers

Here's an attempt to provide validation and formatting for Israeli phone numbers. I used a copy of the US formatter as a starting point.

I've never been to Israel nor dialed an Israeli phone number in my life, but here's what I know from talking to some colleagues and reading this wikipedia page: http://en.wikipedia.org/wiki/Telephone_numbers_in_Israel. Israeli area codes start with a zero locally, otherwise they are just a one-or-two digit number. I tried to validate for the area codes described in the wiki article (only codes starting with 5 or 7 have two digits, no codes that start with 5 have a 1 as the second digit, those that start with 7 don't have 1, 5, 8, or 9, and there are no codes that start with 6), but it probably needs more detailed error messages for those cases. I wasn't sure if the sanitize hook is necessary since the leading 0 won't pass validation is appended automatically when formatting as a local number, but it also may be counter to common sense to forbid it if people are used to starting their numbers with a 0.

This works for my purposes now, but it could use some feedback from someone who is familiar with both this module and Israeli phone numbers (are you out there?).