Add first versions of plugins for MVA reconstruction and classification
Fix compiler-level bugs
Align the package with updates in PECLocalFwk

The package exploits now newly introduced plugins BTaggerPlugin and
EventWeightPlugin; it is aligned with PECLocalFwk of commit
1a59dcef1e1b04137aa6b73942c7990e73717cb3.
Add Dan's plugin for data-driven ttbar

The plugin is added as is, only renamed and removed misleading comments.
Fix a typo in class's name. Turn the region into an enum
Change meaning of collection in JetBTagDataDrivenPlugin

Now it is a mask to choose b-tagged jets instead of a vector of indices
of b-tagged jets.
Align TTbarDataDrivenPlugin with its base class

Now the plugin defines b-tagged jets in the way it is expected to by the
interface. This is the first version that compiles.
Prevent TTbarDataDrivenPlugin from copying jets

Apart from performance reasoning, it breaks
JetBTagDataDrivenPlugin::IsTagged(Jet const &).
Fix a bug in initialisation of reader object in TTbarDataDrivenPlugin
Comment out variances in TTbarDataDrivenPlugin as they are not used
Guard a critical ROOT block in TTbarDataDrivenPlugin
Add a file prefix in TTbarDataDrivenPlugin to resolve paths