Merge pull request #7 from maedoc/master

Fix up docs, CI and organization
more flexible bcast use
implement reduction shape
begin testing shape propagation
Add docs, tests for shape
move vb specific class to vb
reworking the object model
work out model
simplify ir model
simplify reduction shape computation
remove walk in favor of switch to generics
reorg, tests into mod, use generics
update init
consider all modules for testing
tests running again
clean up a bit
generate dot/graphviz files from node graph
significant work on classes & visitors
Merge branch 'master' of github.com:the-virtual-brain/tvb-sym-gen into up
Work out some bugs and provide example of pass + gv generation