Simplify action dispatch

[jameshadfield]

This issue is to highlight the number of actions being dispatched, which is often hard to determine. In general, reducing the number of dispatched actions (i.e. by making fewer actions with more effects) seems to solve a lot of bugs. This should be our general aim going forward.

Please update this table when necessary.

Last updated @ commit 4e27c43

function	n(dispatches) // calls
updateColors	1
changeColorBy	updateColors
populateEntropyStore	1
loadMetaAndTreeAndSequencesJSONs	2 + updateVisibleTipsAndBranchThicknesses + updateColors (total = 4)
updateVisibleTipsAndBranchThicknesses	1 + some anti-pattern modification of redux state
changeDateFilter	1 + some anti-pattern modification of redux state
populateFrequenciesStore	2 or 3
updateTipRadii	1
legendMouseEnterExit	1 + updateTipRadii
applyFilterQuery	1 + updateVisibleTipsAndBranchThicknesses
toggleTemporalConfidence	1 (not a thunk!)
loadJSONs	1 + loadMetaAndTreeAndSequencesJSONs + populateEntropyStore (total = 6)

[jameshadfield]

moved to https://github.com/nextstrain/auspice/wiki/Actions