Remove reporting error functionality.

Throw a generic error when encountering unusable input so that we
can escape parsing of the current cue and/or vtt file, but otherwise
don't report any errors to the consumer of the library.
Match digit characters in test file names.
Order test/test.list file alphabetically.
Update README to clarify JSON file writing.
Fix unescape1 function to have pass correct param.

Fix unescape1() was passing a non-existent var 'i' to the ESCAPE[]
array. Fixed it to properly pass the param 'e' which unescape1()
receives.
Move escape char tests to new test harness.
Move cuetext format tests to new test harness.
Remove duplicate vtt test file.

The duplicate of this can be found in test/cuetext/format/line-breaks.vtt
Add info on how to test parsing cuetext content to README.
Merge pull request #29 from RickEyre/remove-error

Remove reporting error functionality.
Rework tests to use Mocha instead of Tape (#17).