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.
• Build central status handler in UI, which:
  • Handle status bar progress updates
  • Handle search start and stop events to set wait cursor feedback
• Remove all status update logic from individual forms
• Remove all wait cursor logic from individual forms

[jeroens]

Done