Add icon next to a constructor used in a query mapping

[egaga]

Add Dalesbred icon next to constructors that are used in Dalesbred queries, similar to autowired bean dependency icons in the Spring IDEA-plugin.

Benefits:

• quick navigation from the icon to the queries that match the constructor (possibly multiple queries)
• the presence of an icon communicates that it is used
  • no need to annotate constructor separately with @Reflective to avoid warning for unused constructor

Example:

Assuming the only query in the project is
db.findUnique(Foo.class, "select id from foo limit 1");

We have the following class for mapping the id property to a class:

class Foo {

This constructor is used for the query result

  Foo(int id) { // an icon is present in the toolbar
  }

The following constructor has no matching query, so no icon would be next to it

  Foo(int dum, int dam) { // no icon in the toolbar
  }
}

[komu]

I think for starters just making the constructor resolvable with Find Usages would be a good improvement. This probably takes care of unused warnings as well.

• https://confluence.jetbrains.com/display/IDEADEV/Developing+Custom+Language+Plugins+for+IntelliJ+IDEA#DevelopingCustomLanguagePluginsforIntelliJIDEA-FindUsages
• https://confluence.jetbrains.com/display/IntelliJIDEA/Find+Usages+Provider