Don't overwrite user config #517

I have vim.opt.textwidth = 80 in my config but opening rust files it is always set to 99. Initially, I was confused, but then found out that the rust ftplugin has some default values it sets. I can always set rust_recommended_style to false but I think it should rather be opt-in than opt-out.

For example PHP has in it's coding style reference that it must use 4 spaces for indentation¹, but the ftplugin doesn't impose any such restrictions.

Also, as I said, it's very confusing to users when suddenly their settings are overridden. I had to look into neovims source code to find the culprit.

• Rust (.rs) file doesn’t respect my space (tabstop/shiftwidth) rules
• What is changing the textwidth on rust files?
• Use user configured textwidth if it is set

Consider changing the behavior to opt-in, by having the g:rust_recommended_style default to 0.