Update int documentation a bit
Make the if macro accept non-block parameters and implicitly convert them.
Add missing method to simple_boxing implementation
* Rename ContinuationVariable into ContinuationMember since
  they are also used on constants.

* Add a mutable?-attribute to ContinuationMember.

* Make the repl respect immutability of constants.

* Make help into a macro so that it can also work on
  non-method members.