CHECK shared_ptr::use_count at destructor and verbose logging level 1 in
destructor (use --v=1)

++cleanup after } in function there is no ;
cleanup 
}; -> }
++ verbose logging
added clear() member function
new leak test using heap checker from google perf tools
fix compilation
tests
@feelpp/feelpp @Doyeux found one memory leak to a cycling problem in the
shared_ptr for the mesh. The structure could never be destroyed automatically 
see http://www.boost.org/doc/libs/1_54_0/libs/smart_ptr/shared_ptr.htm
regarding cycles. I had to use weak_ptr to fix this. There are probably other
places like that

I have added various tests in testsuite/feelleaks to help us find them.

To ensure that an object wrapped in shared_ptr<> (say p) will be destroyed
when for example p.reset() is called, you can  add afterwards 
CHECK( p.use_count() == 0 ) << "memory leak, object not destroyed";
Merge branch 'develop' of https://github.com/feelpp/feelpp into develop