Distant Horizons - Au Naturel Edit

Pushing some attempts at experimental updates:

• We attempt to cap LOD detail propagation at the coarsest detail level the renderer would ever actually use given the current render distance and quality settings.  I.e. if you have certain high detail levels and low render distance, we do not update or write changes for low quality LODs that would never actually be displayed.  Config entry aggregateLodsBeyondRenderDistance restores legacy behaviour.  Likely immaterial difference for players that play on low level of details and/or high render distance.  Possible marginal gains for players with high level of detail and low (by theoretical standards, not minecraft standards) render distance.
• Adjusted world generation queue's strict "drain nearest bucket before touching farther bucket" with a weighted-round-robin approach.  Nearest bucket still gets roughly 47 percent of picks, but each futher bucket is guaranteed progress.  Aiming to address starvation pattern where nearest bucket was kept full and distant generation never advanced.  Not sure i'm 100% sold on it...
• Added eagerFullHierarchyGeneration config option (default false, for now, might change in future update).  When enabled, world generation for a section produces the full detail hierarchy for LODs all the way down to the user's finest configured rendering resolution on first instance, not just to the level the renderer currently needs.  Aims to reduce coarse-to-fine resource contention issues when player apporaches or arrives in areas previously viewed only from afar.  Comes at cost of disk space required to build and store full detail of all LODs within distant generation radius.
• Changed default LOD render distance from 256 chunks to 128.  As personally, think the 128 radius is more suitable for actual gameplay<-> performance/resource tradeoff in practice.