Removed unused plugins NERDTree and vim-css-color:
* I don't personally use them, so let end user choose.
* It's really easy to add personal bundles anyway.
Replaced the statusline airline with lightline:
* Easier to configure and doesn't mess with other plugins.
* Lacks integration with other plugins by default (by design).
* Requires quite a lot more manual configuration, but "worth" it.
* Still has some quirks, see README.