[FEATURE] - Add Router-Driven Nav

[JSv4]

Better integrate react router so we can share links and use them to drive loading - e.g.:

• opencontracts.com/corpus/1/doc/2/annotations/DFSDFSDS
• opencontracts.com/corpus/1/doc/2
• opencontracts.com/annotations/DFSDFSDS

This will make it far more useful for permalinks.