Fix a bug in DumpClassMvaPlugin when it does not write files
Update the plugin to reconstruct tHq events

The recoil jet is now chosen from untagged jets only. A path to MVA
weights and the list of input vairables are updated.
Update the plugin to reconstruct semileptonic ttbar events

Now the b-quark jets from top decays are chosen from b-tagged jets only.
The MVA weight file and the list of input variables are updated.