Exit with an error code 1 if could not write a compiled JavaScript file or a source map

Currently CoffeeScript reports a success even if it failed to write a
compiled file to disk. This behavior confuses automated tools such as
test runners which may return false positives if a test failed to
compile because of a file lock.
Merge pull request #3592 from mmotorny/master

Exit with an error code 1 if could not write a compiled JavaScript file ...
Rebuild docs
Update changelog for 1.8.0
Merge pull request #3611 from lydell/release-1.8.0

Release 1.8.0
CoffeeScript 1.8.0
Quick spelling fixes
Merge pull request #3616 from epmatsw/spelling

Quick spelling fixes
Remove josh/nack from Examples
Add Atom to Examples
Merge pull request #3618 from josh/update-site-example-projects

Refresh site Examples section
Merge branch 'master' of github.com:martynovs/coffeescript