Compare current version number to that of the latest released neovim
rubygem, rather than a hard-coded version.
Note: The `gem list` command introduced here adds about 4 seconds to the
execution time of the CheckHealth command.
- Use execute() instead of redir
- Fixed logic on suboptimal pyenv/virtualenv checks.
- Move system calls from strings to lists. Fixes#5218
- Add highlighting
- Automatically discover health checkers
- Add tests
Helped-by: Shougo Matsushita <Shougo.Matsu@gmail.com>
Helped-by: Tommy Allen <tommy@esdf.io>
Closes#4932