New generic matching mechanism for matching callbacks

[DonAurelio]

• We updated callbacks models specifying matching callbacks to a generic model complying the metababel model.
• We split the mechanism in two phases, matching and extraction of arguments.
• We validate conflicting function signatures for matching callbacks.
• We lost the flexibility to indicate the order of the arguments, then arguments are passed to the callbacks in the same order as they are defined in the model, since they are extracted recursivelly.

[DonAurelio]

Almost done, I need to refactor the code in metababel bin to avoid the dispatcher's reversal.

[TApplencourt]

Nice \o/ well done! Will review :)

[DonAurelio]

Applied @TApplencourt suggestion to remove the dispatcher's reversal. I will take a look on everything just to be sure we have what we need.

[DonAurelio]

I think we are good to go now, @TApplencourt .