Basic React-based UI to allow re-seeding mapgen

[chrismdp]

• [x] Pixi -> React component
• [x] Create simple Component to set seed value
• [x] Recreate map on seed reset
• [x] Add Redux to manage state better
• [ ] Preserve viewport through setting map dimensions as separate prop
• [ ] Fix incorrect clamping on far zoom out - perhaps pointWidth values not being set correctly on viewport creation?