Move graph computation to Worker

[justinfernald]

Currently the computation of the graph at the launch of the page causes the page to hang, this should be fixed by moving that computation to a web worker. During the time that is loading, the Solve mode should just be disabled. Note that the Edit mode does also use the solver to find if it is in a valid state, so that will likely have to be delt with too.

Another solution is to possibly convert the graph to JSON that can be loaded in and possibly that could be computationally efficient enough to not cause any hanging at the loading of the page