Agree to disagree: label patching

[hlibbabii]

Label hierarchy: definitions of the leaf label should always be fixed and agreed on by all collaborators. However intermediate labels can have different definitions and have different sub-children depending on the task variant.

For the approach to work well, 1) leaf labels should be defined as fine-grained as possible 2) when defining heuristics one should use labels as precise labels as possible, e.g. VariableRenaming instead of Refactoring, so that those who don't agree with a more general label, can still reuse the heuristic.

There should be a default hierarchy, but some task variant can use a different hierarchy, which can be defined by a default hierarchy plus a patch: (e.g. if the following patch is specified docfix: bugFix -> nonBugfix, the default hierarchy will be specified with the only change that docfix subtree would be moved from bugFix to nonBugfix)

If people dont agree on a leaf label, it shouldn't be a leaf label any more.

Another dimension: labels for different languages