Add flops profiler tutorial (#682)
* work on flops profiler tutorial
* update flops profiler tutorial
* add flops profiler tutorial and fix names
* work on flops profiler tutorial
* update flops profiler tutorial
* add flops profiler tutorial and fix names
* fix tailing ws
* fix names
* remove multistep profiling and update docs
* fix cases where functionals and submodules coexist in a parent module, update readme
* fix typo
* always invoke post hook function
* fix module flops sum and update tests
* update tutorial
