Change default parameters and add functionalities to the descriptor interface

• Change the StarPU tags default settings
• Change the nb by default
• Disable the autotuning by default
• Add a user level submatrix function
• Add two user level functions to copy a descriptor structure: with the same data distribution, and only on the root node.

This is a backport of some functionalities developed in !166 (merged)

changed milestone to %Chameleon 1.0.0

added Feature Tests/CTest labels

@all please be aware of the changes in the default parameters and say something if needed.

merged

mentioned in commit ac4a0acc