Add support for custom escaping of labels, and more
Implement custom escaping of description
Ensure that custom escaping callables are actually callable

Plus adding phpdoc
Merge branch 'master' into escape-customizations
Merge branch 'master' into escape-customizations

Conflicts:
	tests/php/test_fieldmanager_field.php
Merge pull request #214 from alleyinteractive/escape-customizations

Add support for custom escaping of labels, and more