* Use goog.requireType when importing I* interfaces
Interfaces have no code, so should never be referred to outside of
(JSDoc) comments, and so the modules that define only interfaces never
need to be goog.require'd - goog.requireType is always sufficient.
This commit fixes imports of all modules whose name matches
/(.*\.)?I[A-Z]*/ - i.e., the hungarian-notation named ones in
core/interfaces/.
* Use goog.requireType when only using import for type specifications
Where a module is imported only to used in JSDoc comments it can
(and should) be goog.requireType'd instead of goog.require'd.
* Remove spurious eslint-disable no-unused-vars
There were a few cases where modules were being imported with
goog.require (because they are referred to in code, not just JSDoc
comments) but were prefaced by a spurious eslint suppress.
Remove these, restoring the invariant that an import gets an eslint
if and only if it is a requireType.
* Remove obsolete Closure Compiler error group
stricterMissingRequire has been superceded by missingRequire, and now
causes a Java null pointer exception if supplied.
* introduce IDraggable interface
* Add parameter to drag methods in IDragTarget
* combines bubble/drag methods on IDragTarget and IDeleteArea to take an IDraggable element
