feat(bin/lmake): add --always-make(-B) option
fix(bin/lmake): save .olean file when makefile doesn't exist
fix(emacs/lean-util): add missing 'cl-' prefix
feat(emacs): define lean-mode as a derived-mode of prog-mode

Fix #52
refactor(emacs/lean-type): clean up
refactor(emacs/lean-type): clean up