[abaqus] automatically overwrite existing files

When a job is launched, Abaqus checks if there are pre-existing files with the same names as those it wants to write. If it's the case, the user is asked whether he wants to overwrite them or not. To overwrite without questions, just have to add "ask_delete=OFF" in the command line.

For instance:
abq6101 job=myJob cpus=8 memory=14GB interactive ask_delete=OFF