refactor(library): rename hop_match to match

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/match): match universe levels

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/match): extend match_plugin interface, and allow them to recursively invoke the matcher

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): 'partial' aliases. closes #24

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(bin/lmake): support multiple targets; add '-C', '-f' options