Periodically forcing all devices to restart the current work to update the ntime value.

Exposing a setting to control the interval (or turn it off)
Exposing more events and removing access to the internal objects. (Avoids threading issues related to accessing lists that are modified internally.)
Adding framework for gridseed support. Cleaning up some code.
Merge branch 'master' of https://github.com/the-best-flash/CSharpMiner.git