initial commit
WIP: dynamic stuff
WIP: change to DynGraph implementation, add switchB
Weak.hs: add mkWeakTVar
Core.hs modifications

  - use lenses
  - use TVars for sync
switching seems done
mv Chain/Graph/Weak to Internal
WIP: add EDyn, run in IO
WIP: I think EDyn is done, need to test it
Show instance for SGInput
more mTrace calls
add chainLabelTree
Syntax: add dynE
add net7 test
more docs to Network type
enable mTrace
more traces
add filter/join to Event
stub out onCreation
add Syntax2 (Signal-style)