Fixes tab creation/moving. 7.3 reverts to old behavior

for 7.2, each window in a tab has the variable requested to be stored as
    a tabvariable. new windows and window rearrangement should trigger a
    synch, making sure each window has the same variable.
Fix previous commit for 7.3
Merge pull request #10 from shinymayhem/master

Fix tab names not updated on tab creation or tab moves