Functions' Comments and help

[mizraelson]

Is there a way to see the help comments for the functions (with fun signature and description)? Similar to the way it is in
IntelliJ IDEA. Maybe with a hotkey or with the cursor over the fun name? And that would be also awesome if I could see the name and the type of the arguments the function needs, while passing the arguments.

[ileasile]

I think it duplicates #73