Rename "master" branch to "main"

[rebeccahum]

With the direction of the "master" term being deprecated in favour of something more ambiguous such as "main" (more context: https://sfconservancy.org/news/2020/jun/23/gitbranchname/), VIPCS should follow suit.

This shouldn't be done until at least 3.0 though since it is a breaking change — any builds that reference master will need to updated properly.

[jrfnl]

I'm in favour of a rename.

There are various common, alternative names though, which each have their own pros and cons. Probably a good idea to consider the various options and to discuss these, before taking a decision on the new branch name.

Here are some typical ones. Happy to hear of more alternatives and for more pros/cons being added.

main

Pros:

• Already chosen as alternative name by a large group of people, causing familiarity.
• Easy for discovery and to switch to for people who use the git command line with auto-complete

Cons:

• Non-descript
• I seem to remember some objections regarding inclusiveness against main as well when the big discussions were raging, but I can't currently find a link.

trunk

Pros:

• Familiar for those who come from SVN.
• Fits in with the "tree with branches" metaphor

Cons:

• No intuitive switch-over when using autocomplete
• Not intuitive for anyone who has never used SVN

stable

Pros:

• Especially when combined with develop (like in this repo), describes exactly what one gets.

Cons:

• No intuitive switch-over when using autocomplete

version-based

Pros:

• Helpful when people are used to semver and want to use the latest, but only from the same major.
• Helpful when a project has a maintenance policy which states that older "majors" still have active support for a period of time after a new major was released.

Cons:

• Fiddly
• Typical reasons to choose this naming scheme do not really apply to this project.

How ?

For a good step by step tutorial on how to do the rename, see: https://www.hanselman.com/blog/easily-rename-your-git-default-branch-from-master-to-main

In addition to the steps in the above tutorial, in my experience, the following additional steps are needed:

• Update the GH Actions workflows - the on: key often refer to branch names to determine whether a workflow needs to run. Those references will need to be updated.
• Update the branch protection in the "Settings" of the repository.
• Update contributor and release documentation which often also has references to branch names.
• Existing contributors/forks may need to update the branch being tracked for locally checked out branches.

[GaryJones]

Closed with #789,