Use the `master` as the main development branch

[4e1e0603]

Use the master branch as the main development branch. Using a develop branch complicates the development process. When you use the develop branch all the hot-fixes have to be merged back from master to develop. There is also no project activity visible to the repository visitors (potential contributors) unless we merge the develop back to master, which happens not so often. At least merging to the master force us to be more critical when we write or review a new code.

• http://endoflineblog.com/oneflow-a-git-branching-model-and-workflow
• https://www.toptal.com/software/trunk-based-development-git-flow

[ondrolexa]

Ok, I think it is reasonable to switch to oneflow model... I just merged current develop branch and discarded develop one.