TorchExplorer 1.1.0: new attach function, multiple forward calls support, documentation, interface improvements

Vega spec version 3d

Release notes:

1. Add attach function for displaying intermediate values in forward
2. Add support for multiple forward invocations in training loop
3. Make input/output/attach nodes show up as Tensor nodes in Vega
4. Add documentation site
5. Fix double-hooking for non tracking hooks
6. Small visual tweaks