forceOnAll will catch exception from resolving Stream element

[runeflobakk]

The expectation from forceOnAll is to force an attempt of execution of an operation on all elements. This works as intended when the elements are already resolved, as they are when passed as an array. But a Stream may resolve it's elements from any source, also sources which can typically fail, e.g. if the element are sourced from an API request. By default, an exception occurring when the Stream tries to yield an element for the pipeline of filters, maps, etc, will abort the Stream terminal operation, and be immediately thrown.

In order to "tap into" the resolving logic, the approach of flatmapping to a (potential) exception using the regular Stream API has now been replaced with a bit more "low-level" use of a Spliterator which will invoke the intended side-effect, and catch any exception which can happen for both trying to advance to the next element, and from the operation itself on wishes to execute on a successfully resolved element.

This subtly changes the behavior of forceOnAll, but I consider this an alignment to what one expects from forceOnAll.

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I also added DiggStreams.describeCharacteristics to get a String description of the characteristics of a Spliterator, which is represented as a bit-string, and difficult to resolve which actual characteristics are enabled. It is not used by any other code in Digg, but was useful when implementing/debugging the FlatMapToExceptionSpliterator, so I decided to include it. It does what it says on the tin, yields a text description, and you should not rely on the String for anything other than information.

[eivinhb]

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