#1031: Methods do not inherit @param tags from parent classes

Currently methods do not inherit @param tags, this change fixes that
by scanning for an inherited element and checking whether it has any
@param tags.
#1031: Descriptions with the {@inheritDoc} were not augmented

For properties, methods and constants the description was not augmented
when using the {@inheritDoc} inline tag. This commit fixes that issues
and now correctly inherits all information.