create unique physical tags across dimensions, so that MED files can be converted into MSH with unique physical groups for GetDP


git-svn-id: https://geuz.org/svn/gmsh/trunk@17711 59c8cabf-10d6-4a28-b43f-3936b85956c4
new GmshOptions "ResetDatabase" to force a database reset before a parameter is changed



git-svn-id: https://geuz.org/svn/gmsh/trunk@17712 59c8cabf-10d6-4a28-b43f-3936b85956c4