Disable status line fiddling if airline is loaded
[Tr] Fix ordering in base colours
Use a brighter foreground for current line number
[Tr] Place signs in their own section
Add specific Syntastic highlights

There are currently the same as the default error/warning highlights, but it
makes it easier to override just the ones you wish to locally.
Add highlighting for git gutter plugin
Highlight wildmenu selection same as per popup
Define highlight for operators
Add highlighting support for nerdtree

This makes nerdtree closer to how the rest of my layout feels.
[QA] Add initial editorconfig er, config