`ParamSpaceSGD` is not a standard terminology

[yebai]

Is there a more commonly used terminology than ParamSpaceSGD? If so, let's rename the folder paramspacesgd and the relevant algorithm names for clarity.

[Red-Portal]

I don't think there is anything more common/standard than ParamSpaceSGD other than, say, SGD or SGVI. But I feel these are not descriptive enough.

[yebai]

Closed in favour of #183 (comment)