v3.1.0 - Added 'random' function option and Indefinite Waits

• Added the 'random' function option which, if defined, is used to source a pseudo-random number to use in operations such as the selection of active children for any lotto nodes and the selection of durations for wait nodes when minimum and maximum durations are defined.
• Wait nodes will remain in the running state indefinitely until they are aborted if no explicit or minimum and maximum durations are defined.
• Added more unit tests.