Fix Unresponsive Method

Fix the unresponsive method offset(). A hard-coded value was being set instead of the value passed.
Fix Weekday Specification

If weekdays were being specified, the day was constantly being set to Sunday due to a bug in the switch statement typecasting the integer zero into a falsey value.
Fix Generation Bug

Switch from less-than to less-than-or-eqal whilst calculating days in the month; the last day of the month would never get reached.
Update Month Validator

Return correct integer values straight away, as there is no need to figure out what the string reporesentation means.
Update Week and Month Validators

Add in the string representation of the integer values of both weeks and months.
Update Exception

Update the FrequencyRequired exception to be an extension of the InvalidCombination exception.
Update Exception

Update the Ininity exception to be an extension of the InvalidCombination exception.
Add Core RRule Types
Getting Ready for Developing RRule
Dirty, horrible code.

But it's really late. I need to sleep. Pushing changes so it's available on work computer tomorrow.
THIS IS A CONCEPT METHOD, and it is no way ready for production (seriously, I am ashamed of this rrule() method).