generator functions + virtual/real context changes

• search:

• all-types-of-interruptable-function
  • generator
  • async
  • async generator

0. DataProviderUtil
   • getChildrenOfContextInRoot
1. navigation
   • navigation in/out/over inside or near all-types-of-interruptable-function
2. errors
   • in normal, Gen/Async/GenAsync functions
3. CG
   • HoleNodes
     • root and non-root holes
   • Stats: context counting