merge parent route meta with children route meta

[stackoverfloweth]

This PR updates createRoute utility to use a new combineMeta to merge child meta with parent (if parent exists). This follows the pattern used for state (and others). Merging meta is just a bit unique in that duplicate keys are allowed as long as the child's property of the same name matches typeof for the parent. The thinking here being that the child can override the meta property of a parent.

This PR also adds a new test suite for createRoute, with tests for new meta functionality as well as combine logic for other parts of the route.

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