Support for 24 hour clock and 12.30 formatting

24 hour should be supported because everyone is not using am/pm formats
* `at 5` is same as `at 5am`
* `at 17` is same as `at 5pm`

Note: `tonight at 5` is still 5pm 

Dot formatting in hours.minutes should be also supported in addition to hours:minutes, ex. `at 12.30`.