[FEATURE] ProteinProphetAdapter

TPP PeptideProphet and ProteinProphet adapter. This version is working for XTandemAdapter idXML results. TPP/xinteract program will do the PeptideProphet analysis on the peptideID results and TPP/ProteinProphet will do the protein inference. 
Tests are added into the SEARCHENGINES folder.
@hroest  The old codes were also written by me, but then I found when the metaValue was not registered, PeptideIdentification::metaValueExists() would return false, even it contained this metaValue("XTandem_score"). FalseDiscoveryRate or others did not register this metaValue "XTandem_score".  Can we use: 
```
if (it->getMetaValue("XTandem_score") != DataValue::EMPTY)
```