Fixes #315 error when a layer does not exist
Fixes #316 Pre-extensions var are required by default
Updated AUCTeX contrib layer with new bindings
Update conventions for help/doc key bindings

`m d` goes under help commands so it is now `m h d`
Update conventions for debugging
Add navigation conventions
Updated Haskell layer

- Uses cabal-repl instead of the deprecated cabal-dev
- Loads company-ghc if company-mode is enabled
- Fixed RET in REPL
- See README.md for keybindings
Add conventions for compiling and building
Reformat tables
Add handlebars/hbs to web-mode file types
Fixes for company-mode for C/C++