* module/rnrs/arithmetic/fixnums.scm (fixnum-width): Make this return an
an exact integer instead of an inexact number.
* module/rnrs/base.scm (assertion-violation): Implement.
* module/rnrs/conditions.scm (simple-conditions): Allow also simple
conditions as argument.
* module/rnrs/enums.scm (define-enumeration): Properly construct empty
enumeration sets.
* module/rnrs/exceptions.scm (guard): Don't restrict the body to a
single expression.
* module/rnrs/records/syntactic.scm (define-record-type0): Expand into a
series of definitions only.