Code and style improvements

[flrdv]

• renamed docstrings describing Set[T] interface methods to be compatible with a community styleguide - to start with a name of actual method. This also allows us to generate documentation more effectively (because go doc by default ignores docstrings that are not starting with an object name)
• in unsafe implementation of set, removed pointer receivers, because unsafe set is already a pointer - because it is a map, and map is a pointer-type, and passing it by value anyway allows us to mutate the origin destination
  • also updated Clear() method. It now REALLY clears the set instead of allocating a new one. All the details are provided in the description of the last one commit

[deckarep]

@fakefloordiv - thanks for the changes I’ll be reviewing this in the coming days.

Overall looks like some nice cleanup.