* Bug: In Katabatic, in AutoHorizontal::_slacken() when slackening
from a METAL2 terminal no longer set the terminal still on the
terminal fixed. Instead use a the new feature of
CntUserNativeConstraints.
* Bug: In Katabatic, in AutoContact, new flag CntUsernativeconstraints
so the native constraint box is specified by the user constraints.
This new possibility is needed because, if a Contact is fixed
the native constraint box *is* bound to it's current position.
But if the related segment is not fixed, and moved, it may move
the Contact with him, loosing the original fixed position.
Now we can remember the wanted position through the user
constraints.
* New: In Katabatic, in GCellConfiguration new explicit management
for 4 globals and one METAL2 (occured for the first time in the
RAM generator).