OPM 139: Linked in the small ert library ecl_well to be used by unittest test_writenumwells.cpp
OPM 139: Rewritten unittest to use ert library ecl_well
OPM-139: Included ert well_const.h - using defines in ertInjectorTypeMask(..). Added method ertWellStatusMask(..)
OPM 139: Fixed wellhead position error: off by one
OPM 139: Calling reserve for vectors, using insert instead of many push_back's