Currently we link to the .txt version of RFC 2445, but the rich text version has better links and navigation.

I would probably change the link in rrule to link to https://tools.ietf.org/html/rfc5545 instead. Technically this is not quite right, since we're mostly based on RFC 2445, but since I'm intending to eventually support RFC 5545, we can accept that all deficiencies in our implementation are bugs, not intended behavior.

A few other places to update to refer to RFC 5545 instead of RFC 2445:

• tz
• rrule test
• rrule Do a search and replace for 2445 -> 5545. RFC 2445 Sec. 4.3.10 is replaced by RFC 5545 Sec. 3.3.10

To do list:

• Update link to https://tools.ietf.org/html/rfc5545
• Update references to 2445 to refer to 5545
• Update references to Sec. 4.3.10 to refer to Sec 3.3.10