Fix ambiguous overloads. Improve == test for sexprs. Remove redundant code

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add foreach for S-expression lists

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Improve consistency of unit tests names

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Fix bugs in hierarchical names module. Add unit tests.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add total order for hierarchical names

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add eqp (pointer equality) tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Add cmp (total order) for sexpr

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