Store one "changed" flag per client; this allows to correctly detect which client needs to be run when a parameter is changed.

Warning: this changes the onelab protocol: now at version 1.1 -- you'll need to upgrade all your clients.



git-svn-id: https://geuz.org/svn/gmsh/trunk@18631 59c8cabf-10d6-4a28-b43f-3936b85956c4