Allow user to refresh etypes cache

[DavidLeoni]

If in step 2 there is no good enough target etype available, the user will open an external etype editor to add it to the knowledge base (or modify an exisiting one). At this point he should be able to tell odr to refresh etypes cache to be able to use it. Also, clients (open data schema matcher, column recognizers, disi client), should refresh eventual cache.

A good system would automatically refresh cache periodically, but for now that introduces a dangerously parallel thread which we don't really need. For fixing the old version of the clients, I have to think about what to do.

[DavidLeoni]

Closed in branch-0.3

Added button in the upper right corner to both refresh etypes and invalidate cached concepts. Overall, Schema matcher performance seems to be improved.

Integrated with

• Disi Client etypes and concept caching: Implement etype caching disi-open-data-client#24
  and Implement concept caching disi-open-data-client#23
• OpenData Schema matcher instances caching: Entities should be cached opendata-schema-matcher#6