fix type + indent
Fix exceptional implicit constructor and result type of then/recover.

Make exceptionals constructor explicit.
Adjust the result type of the then and recover functions to the result
type of F.
Comment the try_catch inside then and recover.
Let make_expected take only T as parameter as the variadic needs
make_expected<T,E>(...)
Change next for then in tests.
Activate tests.
Update master tests.

Update cpp11 to avoid reduncdancy of feature definition.
Update tes_expected.hpp to take care of new implementation of
then/recover without try_catch.