Decouple Most of OPM-Common From LibECL

This commit takes a pass at the implementation files in opm-common
and removes references to libecl functions where practical.  In
particular we switch to using types from C++'s standard library (and
Boost.Filesystem) to achieve the effects of the interfaces being
replaced.

We also insert direct calls to Posix function fnmatch() to preserve
existing pattern matching behaviour (well lists and well templates).

opm/parser/eclipse/EclipseState/IOConfig/IOConfig.hpp

@@ -20,7 +20,7 @@
 #ifndef OPM_IO_CONFIG_HPP
 #define OPM_IO_CONFIG_HPP
 
-#include <boost/date_time/gregorian/gregorian_types.hpp>
+#include <string>
 
 namespace Opm {