[ANN] DispatcherCache.jl hash-graph adaptive persistency for task graphs

DispatcherCache.jl Adaptive hash-graph based persistency mechanism for Dispatcher.jl computational graphs.

The basic principle is to speed up the execution of task graphs by re-executing the minimal number of nodes possible (i.e. those which have arguments, code or dependencies changed).

The package still has a few rough edges and lacks extensive documentation however the API is simple and stable enough.