Add missing customization group
Move faces into a separate customization group
Remove obsolete variable
Move fringe icon into separate function
Make error indication customizable
Replace association list with a simple cl-case
Simplify hook setup and teardown
Get rid of deferred checking

This deferred checking stuff was just a super-complicated way to check
only visible buffers.  So let's just do this right away: Inhibit all
syntax checks in invisible buffers and recheck buffers if they become
visible again.
Unbreak Rubocop tests

Grr, @bbatsov ;)
Fix byte compiler warning in Rubocop tests
Get rid of superfluous warning
Simplify some conditionals
Clean up requires
Make optional google-this library available for development
Delete garbage character

Regression from d9f248a8
[Fix #127] Update Elixir checker for Elixir 0.8.2
Use new -when-let from dash.el 1.2

Bump dep accordingly

Thanks @magnars, dash.el gets more awesome every day!
Fix type error

Introducing `-when-let` to `flycheck-fix-error-filename` broke the
return value of this function, because it would return nil now for
errors without filenames.

Fix this by moving the return value to the top-level of the function.

Regression from 89ed9a2.
Fix punctuation

[ci skip]
Teardown Flycheck if Emacs is killed