add doc:
  gsl interface 
  imax of tableau 

Short time:
 build a true aniso 3d adaptation example
  to day bug in interface of mmg3d with metric and in tetgen ...


long time: 

Add Finite Volume interface. 

Track: 

add the sup of a function on a mesh
real uinfty=sup(Th,abs(f));
real uhinfty=sup(uh); 


Newton algorithm.

automatique scheme for time depend problem:
dt(u) or u_t

implicite:
problem a(u,v, sheme=Euler , dt = 0.1, tinit = 0, tfinal = 10 , previous=[u1]) = 
  int2d( u_t*v + dx(u)*dx(v)+dy(u)*dy(v) ) ;
  
explicit:
problem a(u,v, sheme=thetaScheme(0.5) , dt = 0.1 , tinit = 0  , tfinal = 10 , previous=[u1]) = 
  int2d( u_t*v) + int(dx(u1)*dx(v)+dy(u1)*dy(v)) ;



