Bump spine core to v4

Bump to 0.5.12

Merge pull request #65 from MassiveHeights/v0.6.x-dev

v0.5.11

changed author

version bump

Merge pull request #50 from MassiveHeights/v0.6.x-dev

v0.5.8-stable

Merge pull request #47 from MassiveHeights/v0.6.x-dev

v0.5.7-stable

Merge pull request #46 from MassiveHeights/v0.6.x-dev

v0.5.6-stable

Merge pull request #45 from MassiveHeights/v0.6.x-dev

v0.5.5-stable