feat(frontends/lean/server): use alias (if available) in FINDG command output

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): add '?' for inspecting the type of any expression, it produces a EXTRA_TYPE info entry

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): add '[protected]' modifier

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(library): use '[protected]' modifier

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(emacs/lean-syntax): add syntax-highlight for declaration modifiers

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): rename 'using' command to 'open'

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
checkpoint for imenu
checkpoint
checkpoint