The axmol branch management

[halx99]

branches

• dev: this branch should be stable, accept any pull-request, current 2.x release tag also cames from this branch
• experimental: this is the temporary early experimental researching branch, accept big changes, big features pull-request, any changes with full-tests of this branch should be merged into dev branch in the future. and before merge changes of this branch into main, should create a stable branch from dev, i.e. 1.0.x/1.x, the backup branch only accept bugfixes. once this branch was merged into dev, this branch should force identical to dev and will be deleted