[Fix #391] Ask for confirmation before deleting a file that's not under VC
Use Prelude's prelude-mode

Conflicts:
	core/prelude-mode.el
Add `prelude-github`

Conflicts:
	core/prelude-core.el
Move custom keys into init-keys.el
Enable smartparens-strict-mode in Lisps
Add smartparens
Disable smartparens
Revert "Enable smartparens-strict-mode in Lisps"

This reverts commit 800f94b012eb9fe4acfa1954a9dc951d3602a551.