* 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.
* add unsetControlCHook to remove a Ctrl-C hook after it was set
Adds the inverse proc to setControlCHook in order to lift a Ctrl-C
hook after it has been set.
* remove check for noSignalHandler in system/excpt.nim
