Fixed bug #20044 : PSR1 camelCase check does not ignore leading underscores

Required the PSR1 standard to use its own sniff rather than rely on a generic one. This also stops function names from being checked as the PSR1 standard only mentions "methods" under the class heading.
Squiz and MySource File and Function comment sniffs now allow all tags and don't require a particular licence
Merge branch 'master' into report-memory-improvements