Many things, mainly better encoding support and automatic length things:

* more stringent RFC compliance with line endings
* message length trimming for huge messages
* message splitting
* helpers for managing message length and automatic string substitution
  trimming
* Reworked dispatcher to create events only when necessary and as late
  as possible
* smarter maximum message length determination by noticing prefix length
* basic nickserv identify support
* refactored settings to be a bit more concise and less bad