Remove import warnings

See merge request eclipse/aidge/aidge_core!129

Merge branch 'fix_import_warnings' of gitlab.eclipse.org:eclipse/aidge/aidge_core into fix_import_warnings

- Change Softmax_Op 'axis' attributes from int to size_t
- Change Transpose_OpImpl to TransposeImpl
- Change snake-case to camel-case names
- fix tests according to AvgPooling_Op changes

- add Tensor operators +,-,*,/
- add __repr__ funciton to Tensor
- add operator constructor to each python binding
- fix identity_op Base class declaration in binding

- Move code definition in an external cpp file in src directory
- Remove InChannels, OutChannels, NbChannels from the list of attributes as they are only used for creating the associated Producer. They are kept as parameters of the Operator factory function to continue creating Weight and Bias Producers automatically. The number of in/out channels is now based on the Weight parameter
- 'Conv_Op::inChannels()', 'Conv_Op::outChannels()', 'ConvDepthWise::nbChannels()' functons added

Improved "not implemented" errors

See merge request eclipse/aidge/aidge_core!130

- Change Softmax_Op 'axis' attributes from int to size_t
- Change Transpose_OpImpl to TransposeImpl
- Change snake-case to camel-case names
- fix tests according to AvgPooling_Op changes

- add Tensor operators +,-,*,/
- add __repr__ funciton to Tensor
- add operator constructor to each python binding
- fix identity_op Base class declaration in binding

- Move code definition in an external cpp file in src directory
- Remove InChannels, OutChannels, NbChannels from the list of attributes as they are only used for creating the associated Producer. They are kept as parameters of the Operator factory function to continue creating Weight and Bias Producers automatically. The number of in/out channels is now based on the Weight parameter
- 'Conv_Op::inChannels()', 'Conv_Op::outChannels()', 'ConvDepthWise::nbChannels()' functons added

Use the ordered nodes API in Sequential() in order to preserve the user declaration nodes order

See merge request !128