Fixes #115 - Correct snapToLines assertion, safety checks, linewrap

- Assert snapToLines == TRUE rather than FALSE, per the spec
- Assert errorCount == 1 before error condition asserts to prevent bad
  access
- Use convenience function for error assertions to shrink code
- Wrapped lines at 80 columns
Merge pull request #115 from caitp/issue-115

CueSettingLine.BadKeyword incorrectly ASSERT_FALSE(snapToLines())