implement listSmoofFunctions

[jakob-r]

Would be nice to have a function that lists all functions (and functions with specific tags and with a specifc dimension).
Then we could also easily generate an overview of all functions with neat plots.

[jakobbossek]

Currently there are filterFunctionsByTags and makeFunctionsByName. However, we cannot filter by dimensions, only be scalablility. Maybe I should extend the abovementioned functions?

[jakobbossek]

@jakob-r Does this work for you or do you think we need this listing function?

[jakob-r]

I wasn't aware of filterFunctionsByTags so I am already partly satisfied but still I think to filter by dimension would be handy. But you are free to close this issue as I do not need it urgently.