[#53] Concurrency Bug Fixes

[whimxiqal]

• fixes #53
• fixes #54
• fixes #51
• Introduces a caching layer to handle common waypoint data access, like tab completion
• Handle tab completion synchronously on the main thread by using cached data
• Handle player location accessing synchronously on the main thread
• Send warnings for improper internal access of non-thread-safe components from async threads
• Paths no longer send preliminary chunk cache requests
• The central chunk cache requests more chunks for chunks surrounding the requested one
• The central chunk cache completes a limited number of chunk requests per tick
• Properly synchronize the stats manager
• Change scope name validation to accommodate Minecraft usernames