Laurent Rineau be079cb5a3 Fix compilation with Boost-1.56 and later ...

In Boost-1.56 and later, with C++11, boost::optional::operator bool() is
explicit.

2015-01-13 16:21:04 +01:00

..

CGAL

Fix compilation with Boost-1.56 and later

2015-01-13 16:21:04 +01:00