Running searches need to be better protected and terminated

[jeroens]

This requires safety at several levels:

• Cannot close a form that leaves search running
• Cannot close core when a search is running
• Cannot run anything else when a search is running
• Cannot start search when something else is running

[jeroens]

Additionally, the scientific interface should centralize status feedback for running processes. This should no longer be triggered from individual forms; it is the core progress that should be reported, NOT UI progress.

To update this, the following is required:

• Send cProgressMessage for any start, step and stop of any process. This applies to all searches, lengthy operations (save, load, and import), running value chains and network analysis, etc. This replaces most cApplicationStatusNotifier calls.
• The central status handler in UI, which is now AppLauncher, is the only component responding to cProgress messages to update the status bar. This requires no changes.
• The central form state handler must be extended to link running searches to specific interfaces. This link does not exist yet.
• Move status update logic from individual forms to core operations where possible
• Move wait cursor logic from individual forms where possible

[jeroens]

Done