Fix cigeneral_unittest

Removed C comments from head of test/unit/cue-ids/basic_pass.vtt
Wrapped lines in cigeneral_unittest.cpp to 80 columns
Make use of helper functions for error checks where possible
Expect rather than assert where possible
Safety checks to prevent buffer overflows/out of bounds access
Merge pull request #344 from caitp/cigeneral_unittest

Fix cigeneral_unittest