Filter dimension for the first conv1d operation

[wwang2]

Hi! Thanks for the implementation

I think there might be some problem when implementing the conv1d layer here:

https://github.com/cxhernandez/molencoder/blob/1d7e208713d8e97683650b1bbc37a9fa298b4ce0/molencoder/models.py#L56

I think the definition of o' and i' are swapped. The input filter dimension should the number of possible characters (35), and `c' should be the padded SMILES sequence length.

Just want to confirm this detail. I can submit a PR if that is correct.