tools: automatic reload when changes are detected for some resource types

[dbartolini]

Currently, one has to hit F7 each and every time he wants to reload changed resources.

For some resource types it would be good to offer the ability to choose whether to keep the current behavior or automatically reload whenever a change to such file types is detected.

• data-compiler: send change notifications to connected clients
• editor: preferences: add combobox "do nothing", "reload on change" etc.
• editor: trigger compile + reload based on preferences setting