Simplified renaming of various core functions and classes

[mikeheddes]

The aim here is to align in naming with PyTorch and improving clarity of the API. Therefore all PyTorch Tensor subclasses are now suffixed with Tensor.

Breaking changes:

• VSA_Model -> VSATensor
• BSC -> BSCTensor
• MAP -> MAPTensor
• HRR -> HRRTensor
• FHRR -> FHRRTensor
• empty_hv -> empty
• identity_hv -> identity
• random_hv -> random
• level_hv -> level
• thermometer_hv -> thermometer
• circular_hv -> circular
• cos_similarity -> cosine_similarity and aliased as cos
• The function signature of hypervector creation now takes in a string instead of the VSATensor type

Additional changes:

• dot_similarity is aliased as dot
• SDM renamed as SparseDistributed