Fix of GH#43 Assertion Fail for localGridIndex
The grid number associated with an ert grid was an ID and not an index.
In addition: Fixed unrobustness handling wells with no data.
Now the /Troll/MSW_LGR/2BRANCHES-CCEWELLPATH-NEW-SCH-TUNED-AR3.EGRID file loads( Have tested only two timesteps ).
p4#: 22321