PMC proposals/Overhaul

I propose to overhaul the Bylaws in this manner:

• https://github.com/apertium/organisation/pull/13 - discussion is happening here.
•  https://github.com/apertium/organisation/blob/overhaul/Bylaws.md
•  https://github.com/apertium/organisation/blob/overhaul/CLA-optional.md

Goals of the changes

• Prepare for creating a legal entity for Apertium. But that will come later; this overhaul is needed regardless.
• Rename Developer to Contributor.
• Rename Committer to Voting Member. Not merely Member, as that would be confused for member of the Github organisation. Anyone can be a Github member, but it has to be a conscious choice to want to be a voting member.
• Separate the definition of Contributor with commit access and Voting Member. Being a voter should not be tied to having commit rights. This tie made sense with a monorepo, but it really doesn't make sense with split decentralized repos.
• Empower Contributors to do what they're effectively doing anyway (make releases, grant access), while still keeping PMC oversight for big changes.
• Recommend a Contributor License Agreement, but at least require that licenses must be clear. I'm tired of resolving licensing issues.
• Raise inactivity limit to 1 year.
• Formally ensure we reduce the bus factor and security risks.
• Change PMC voting system to STV.
• Formalize tie-breaker mechanics, since it just became relevant.