Anchor setTarget allows invalid strings.

[vardumper]

Fix this $anchor->setTarget('ouch');

Since ouch is not a valid value, it shouldnt do anything (or throw an error).

[vardumper]

this is a false positive. the target attribute should allow defining a framename. (whatever string, so it shouldnt be limited to pre-defined TargetEnum cases.

[vardumper]

added more tests, harmonized all setTarget methods to be no-op on invalid string values. filter out invalid strings.