Implementation of G-CNN

[yuehhua]

• [ ] GConv layer (G-convolution)
• [ ] GPool layer (G-pooling)
• [ ] GCNN example

Ref. Group Equivariant Convolutional Networks

[yuehhua]

Similar work: ebekkers/gsplinets

Ref. B-Spline CNNs on Lie Groups

[5hv5hvnk]

we need to add this in a new file to this path right src/layers/