See proposed UI integration

• On a tracker report, in search area, I can switch to "Export" mode
• The expert mode is a simple text area with select box for the fields that can be searched
• Grammar
  • fields type: string & text
  • operators: (), AND, OR, =
• The query is save in sessions & in DB (for reuse as report)
• There is limited error management
• Technically speaking
  • parse this grammar & generate AST
  • generate SQL from AST
    • manage permissions
    • introduce a limit with the depth of AST (configurable per site) in order to prevent too complex queries
• Examples:
  • summary="test" and description="stuff"
  • (summary="test" or description="stuff") and free_text="stuff"