With this commit the IWEL[ActWCtrl] is assigned a value independently of the
wells OPEN / SHUT status.
With this PR the index enum value Status is used instead of the previously used
item11. Also numerical constants are introduced for eclipse status values for
Shut, Stop, Open and Auto.
This commit changes two aspects of restarts where well and group information is
assembled from the restart file:
o We require the restart date to be present in the Schedule file as a DATES
keyword.
o SKIPREST behavior is implemented unconditionally for restarts with restart
files, even if the SKIPREST keyword is not present.
