restructuring for easier maintenance

- creating src packages when things can't be installed via
  actual system package
- neovim srcpkg is being worked on now

vars/neovim.yml

@@ -0,0 +1,5 @@
+---
+git_repo: https://github.com/neovim/neovim.git
+version: 0.10.3
+build_type: Release
+install_prefix: /usr/local