[scripts] A re-write of the benchmarks script (#53)

* [script] Renew the runBenchmarks_script.py

* [doc] Document script usage

* Fix formatting in Scripts.md for benchmark usage

Updated documentation for runBenchmarks_script.py usage.

Author: th-skam

doc/Scripts.md

@@ -0,0 +1,41 @@
+# Scripts Folder Contents
+
+The Scripts folder has a collection of python scripts to provide basic utilities.
+
+## runBenchmarks_script.py
+
+```
+SOFA Scene Benchmarking Tool
+
+Usage:
+    python benchmark.py -config benchmark.json
+    python benchmark.py -config benchmark.json -n_tests 10 -timeout 180
+
+Config file format (JSON):
+    {
+        "sofa_exe":   "runSofa",
+        "iterations": 110,
+        "n_tests":    5,
+        "warmup":     2,
+        "timeout":    120,
+        "output":     "log.benchmark",
+        "cases": [
+            { "name": "baseline",   "scene": "scene_baseline.scn" },
+            { "name": "refactored", "scene": "scene_refactored.scn"     }
+        ]
+    }
+
+    - `sofa_exe`: command to run (to choose SOFA version).
+        - Default: `runSofa`
+    - `iterations`: # of time steps to run in batch mode. 
+    - `n_tests`: # of tests to run. Mean & std of FPS are computed. 
+    - `warmup`: # of times to do a dry run to avoid false reports due to caching.
+        - Default: 2
+    - `timeout`: # seconds to run before killing process. For stale runs that crashed.
+    - `output`: Name of the file to report results.
+        - Default: "log.benchmark"
+    - `cases`: Which scene files to use
+
+
+All top-level config keys can be overridden individually via CLI arguments.
+```