feat(shell): add '--hott' command line option

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): add 'import' command, add command line option for setting number of threads

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(frontends/lean/parser): style

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(shell/CMakeFiles): typo

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(kernel): set module_idx on theorems, otherwise we are not able to import theorems that use opaque definitions

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/builtin_cmds): add 'set_option' command

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/builtin_cmds): add 'print options' command

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