camelCase rrule options

[yogurtandjam]

Currently, there is no library that handles both parsing and writing of icals.

Fortunately this library follows almost identically the format required for https://github.com/sebbo2002/ical-generator

The only significant difference being ical-generator expects RRule option properties to be camelCased while in ical they are flat cased, which is interesting because within RRule, origOptions is camelCased.

The purpose of this is not to try to coerce this library, which does a great job btw, into following patterns of another library arbitrarily, but in the hopes that by following standard javascript casing styles we can bring further consistency across related libraries so they may be easily used together.

What do you think? I'd be more than willing to submit the PR myself