feat(emacs/lean-input): add lean-input-export-translations
feat(emacs/lean-info): add PROOF_STATE info

Close #259
feat(emacs): extract proof state information attached to ","
feat(emacs/lean-settings): add lean-show-proofstate-in-minibuffer option
feat(emacs/lean-type): output INFO to *lean-info* buffer in addition to minibuffer

Close #260
fix(emacs/lean-syntax): fix Type1, Type2 highlight
feat(emacs/lean-mode): add lean-info-mode for "*lean-info*" buffer
test(emacs/lean-info-test): add test for proofstate info
fix(emacs/lean-info): proofstate display problem
fix(library/definitional/projection): remove redundant 'error in'
fix(frontends/lean/info_manager): suppress useless tactic type information, closes #277
fix(emacs/lean-flycheck): should accept error messages with empty lines
feat(library/tactic/proof_state): add empty line between goals, closes #281
fix(frontends/lean/elaborator): incorrect error position in begin-end block, fixes #276