Throw exception on required parameter absense

Right now if a tag (in template) is called without a required parameter, then developer gets some weird errors back, which doesn't always tell where the problem is.

I suggest to:

1. create a TagProcessor::requireTagParams property, that would contain a list of required parameters
2. in TagProcessor::setRequiredTagParams method define required parameters for each tag
3. in TagProcessor::ProcessParsedTag we, only in debug mode, check, that all required parameters are present and of not show an error