ocl: updated tuned parameters, improved tuner, adjusted kernel

[hfp]

tune_multiply.py

• Explicit/keep instance of SmmTuner which enables saving the final state even after an exception/error.
• Ensure SmmTuner is initialized once (manipulator method is apparently called multiple times).
• Only call save_final_config if it is not the seed-configuration.
• Support parameters that cannot be expanded in value-range.
• Implemented option to delete outperformed JSONs.
• Print additional info for retainable/deletable files.
• Fixed populating tunable/fixed parameters.

Tuning on multiple devices (tune_multiply.py)

• More robust file manipulation when running with MPI. Create dot-files on a per-device basis.
• Ensure to initially expose all devices. Fixed parsing initial configuration. Code cleanup.
• Support tuning parameters on multiple device using MPI.
• Rebuild CSV-file only on master-rank.

kernels/multiply.cl

• Replaced short with SINT def., and changed to signed char.
• Reduced number of choices for AA, AB, and AC parameters.
• Expand value-range of tunable according to seed-value.
• Adjusted some loop induction variable type.
• Fixed synchronization issue.
• Code comments.

Documentation

• Section about "Advanced Tuning" (utilizing multiple devices).