Continued work on #3018. Fixed stack trace copy over for additional optimizations, fixed errors in previous commit and inclduded addditional tests.

Implemented tests to check stacktrace is copied over for several opts. Implemented stacktrace copy over for more opts.

[ENG] Doc, blas timing, better error, doc to use pydot-ng, function_dump now strip some stuff.

fix get_scalar_constant_value error message

Remove useless reshape

Change @ caractere to #, to prevent collision with github convention to ...

[CRASH] Debugmode

Fix pydotprint issue for Python 3

Better error in Scan

Two-layer hierarchical softmax

Remove trailing semicolon

Fix comparisons with None

Dict can be litteral