Слияние с default

fixed error handling for chained actions

fixed: the error handler should not handle handlers errors

fixed promise chaining behavior, the error handler doesn't handle result or cancellation handlers exceptions these exceptions are propagated to the next handlers.

minor changes

working on diagnostics

Added tag release v2.1 for changeset f1da3afc3521

Слияние с v2

bump version to 2.1

Слияние с ref20160224