Improve STFLEngine and OverviewPanel.
The egine stores the last 200 user query commands and uses them to
improve the suggestions. It also supports "additional" commands,
commands that are executed once per query execution.
The OverviewPanel supports opening calls via the "additional" command
"open".
Merge pull request #45 from CVVisualPSETeam/experimental

Improve STFLEngine and OverviewPanel.