[ENHANCE]: Error message for plugin.

[Typocalypse]

Description

This enhance the error message in Vim plugin, added a checks for minimum Vim version and Python 3 support in the vim plugin with clear error message.

Checklist - did you ...

• [x] Add an entry in CHANGES.md if necessary?
• [x] Add / update tests if necessary?
• [x] Add new / update outdated documentation?

[Typocalypse]

@nirs Is it a good idea to display messages with the current version and the required version in the error message, or is it just unnecessary overhead?

[nirs]

@nirs Is it a good idea to display messages with the current version and the required version in the error message, or is it just unnecessary overhead?

I don't think that showing vim version is helpful to users. The only useful thing is the required version, in case you run a very old vim. Even if this was useful, vim version is displayed when you start vim and available both via vim --version and using the package manager.