`EditSession.setWrapLimitRange` should set a new object to `this.$wrapLimitRange`

This fixes a bug where if you have 2 instances of EditSession and you
`setWrapLimitRange` on one of them it would affect the $wrapLimitRange
on all other instances of EditSession.
Merge pull request #1591 from rmsmith/wraplimitrange_bugfix

`EditSession.setWrapLimitRange` should set a new object to `this.$wrapLi...