Holy refuctoring! Sorry for the change, but some libraries were having naming conflicts. You can define SPINE_SHORT_NAMES before including spine-c headers if you want to use structs and functions without the "sp" prefix, as it was before.
Changed from New BSD to a custom license. The new license requires a Spine license to use the code. If you have a valid Spine license, you can do whatever you like with the code. This should not be a problem for anyone using the runtimes with Spine, nothing changes. If using the runtimes without a Spine license, you now need a Spine license. This is because the runtimes were created explicitly to be used with Spine.