Merge branch 'master' of https://github.com/MARCspec/php-marc-spec

styleci fix

removed debugging test

bug undefined variable in __toString

abbreviation in examples

abbreviation for indices

fixed style

Merge pull request #6 from MARCspec/analysis-XV3xOq

Applied fixes from StyleCI

travis teest php 5.6

Merge pull request #5 from cKlee/master

added indexLength+invalid regex

Merge pull request #4 from cKlee/master

added charLength for  offsetExists