feat(frontends/lean/decl_cmds): allow parameters with different types to be declared using the same 'parameters' command

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(emacs): syntax highlight bug

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/hott): use new 'parameters' command

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/hott): use new 'parameters' command