editors/neovim: Update to 0.5

While here, generate the runtime data files automatically. Enumerating
them stopped being fun.

There are major new features in this release, the most notable being the
inclusion of native support for LSP (Language Server Protocol) and a
native parser/AST generator. These can be used to do intelligent code
analysis and completion, without requiring external scripting providers.

Also, the Neovim config file(s) can now be written entirely in lua
instead of (or in addition to) Vimscript.