* Error -> Defect for defects
The distinction between Error and Defect is subjective,
context-dependent and somewhat arbitrary, so when looking at an
exception, it's hard to guess what it is - this happens often when
looking at a `raises` list _without_ opening the corresponding
definition and digging through layers of inheritance.
With the help of a little consistency in naming, it's at least possible
to start disentangling the two error types and the standard lib can set
a good example here.
* Make sequtils.zip return seq of anonymous tuples
Earlier the tuples had named fields "a" and "b" and that made it
difficult to assign the zip returned seqs to other vars which expected
seqs of tuples with field names other than "a" and "b".
* Make sequtils.zip backwards compatible with Nim 1.0.x
