Allow debug to report multiple invocations

[kaiyaok2]

This PR addresses the idea in (#53) to report many invocations from all seeds that can reproduce error.
3 changes are made w.r.t the original PR:

• Resolve code conflict with the latest master branch
• If a test is ND (falsely identified as ID by NonDex, which is quite common), reportDebugInfo() , which subsequently calls failsWithConfig() can return null even if being run with the same "originally failing" configuration. Then, the list allFailingConfigurations can contain null entries, which causes NPE when iterating through the list. The solution is to add a null check to avoid NPE thrown by makeResultString().
• The original PR did not add the results found by linear search to the output list. This PR corrects it.

[darko-marinov]

The code looks good enough to me to merge so we can release sooner the next version of NonDex to support Java 9+.

[darko-marinov]

The code looks good enough to me to merge so we can release sooner the next version of NonDex to support Java 9+.