[exploration] Init commit

The module is fonctionnal but deserves more testing.

Unit test is valid (but may be completed).

Frontiers attributes are not handled now
(required for planning and decision making).

No Python Bindings.
[exploration] Getter are const functions
[exploration] Python for exploration (WIP)
[exploration] Improve API
[exploration/python] displays data correctly
[python] fix pull #3