[substr] ensure position is within range
[date/time] validate strings prior to taking substr()
[infotypes] improve validation of strings
[cddb] improved string validation
[networkosx] improve validation of commandline return strings
[cosmetic] adds comments regarding assumptions of string format
[videodb] fix query in GetMusicVideoAlbumsByName
[cosmetics] adds TODO:STRING_CLEANUP to various places in the code that could do with a spring clean
Merge pull request #3654 from jmarshallnz/substr_fixes

Validation substr() usage prior to plowing ahead.