Development: add next branch

[purerosefallen]

Changes like #2393 and #2386 would require changes from ocgcore, and those changes should be applied when next update releases together with a new distribution.

And to make fixing changes apply quickly to servers, we would have to maintain a version of scripts that rely on the previous released ocgcore, that functions well and can be quickly applied. In the past we had to manually revert those changes requireing the next core version, with something like mycard@86d9be5. What's more, there are even more works like mycard@3e7fb21 to switch the scripts relying on the latest core back to what it looks like on the master branch.

That's why I would suggest we split the versions during development phase to make script updates smoothly. We could add a next branch, and open those PRs requiring core changes to this branch.

[mercury233]

not funny