Fix sync issues

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This MR:

• Reworks most of the sphynx code to no longer wrap specs::World and to allow operations on subsets of the entities in the ecs world (moved to common::sync, unless @zesterer would like a sphynx MR, since the code is significantly different from the original sphynx)
• Stops the global syncing of entity creation
• Properly re-sends an entity that returns to a client's viewing range
• Eliminates the syncing of the Projectile component since it is not needed client-side
• Stops syncing of Stats when just the time since the last health change is incremented
• Fixes the NaN which was producing overflows in the physics system
• Makes pushback no longer affect character orientation
• Makes melee attacks aware of Scale
• Upgrades to specs 0.15.1 (awaiting merge of my version bump of specs in specs-idvs @xacrimon)
• Fixes #377 (closed), #359 (closed)