Revert "Quit in a way similar to help buffers'"

This reverts commit 519a18107cb0477cfae7b92d11c0c61190a9bdc0.

Conflicts:
	mu4e/mu4e-view.el
Merge pull request #364 from sabof/revert-519a181

* mu4e: revert "Quit in a way similar to help buffers'"