* Introduce execution mode for clarity and extensibility; Change Python APIs accordingly; Replace DisableSequentialExecution API with EnableParallelExecution for clarity.
* Fix cuda build
* Modify the test slightly
* Make C and C# APIs consistent with Python.
* Fix broken link and minor wording updates
* Update links to use relative paths
* Update sample section organization
* Fix a few more links
* Update links to relative paths
* Fix link urls
* Update links to relative paths
* Update link to perf test doc page
* Update links to relative paths
* Update to relative paths for links
* Update link