Default values for view helpers based on context
We should supply a mechanism in the "ViewHelperNode" which will merge the given parameters with certain default parameters.
The default parameters should be context dependent (However, we don't know yet how this might look like).
This would be helpful for numerous cases:
- <f3:uri.linkTo> -> "action", "controller", and "package" arguments could be supplied if no other parameter given
- Link parameters - we could realize something like "keepPIVars" with this feature
- <f3:image> tag - supplying default parameters for maxWidth, maxHeight, ...