Push back on containers

This branch extends the push_back() on buffer, container and table so that : 
 - push_back on a scalar lienarize the container and add at the end
 - push_back of another container concatenate on the last dimension

Optimization of buffer capacity on resize also have been added. By default, a growth factor of 2 is used but can be defined through a macro on system where such behavior has to be fine tuned.