feat(emacs/README.md): add instr. for MELPA; add whitespace-cleanup-mode
fix(emacs): use cl-case, require cl-lib
fix(library/standard): remove long comments introduced by b2c2d1d
feat(emacs): use optional package when required
feat(emacs/lean-setting.el): add lean-rule-color custom-var
feat(emacs): provide an option to disable lean-flycheck
feat(emacs): add lean-flycheck-turn-on/off/toggle
fix(library/unifier): make sure the imitation step is type correct, fix ensure_sufficient_args

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(kernel/error_msgs): change type mismatch error messages, closes #33

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/scoped_ext): force user to end a scope with an identifier matching the one used in beginning of scope, closes #30

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): make sure all scopes are closed in the end of the module

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(library/standard): add missing 'end' of namespace

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
perf(library/unifier): improve check_imitation performance

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/explicit): allow 'as-is', 'explicit' and 'implicit' annotations to be saved in .olean files

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
perf(library/unifier): improve 'assign' method, keep old version

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/standard): add classes for relations
feat(library/hott): begin porting Coq HoTT
feat(library/hott): add theorems about paths
feat(library/hott/path_groupoids): add more theorems