Early game leveling

Adds support for early game leveling via FabulousFourLeveling function.

Notable additions
**HeroLevel**: Get/Set current hero level
**TargetHerolevel**: Get/Set levelling target for a hero
**LevelHeroTowardTarget**: Selects an appropriate leveling strategy and levels a given hero towards their target level
**TargetHeroLevelReached**: Determines if heroes are at their target level
**BuyAllUpgrades**: Purchases any available hero upgrades

Other fixes
Sometimes switching between pages near the bottom is janky. Page scrolling has an internal fix for this now