“Soft kitty, warm kitty, little ball of fur. Happy kitty, sleepy kitty, purr, purr, purr.” All Big Bang Theory fans know that this lullaby is the only thing that can calm Sheldon down to a sleepy state. However, what they might not be aware of is that it now has become the subject of a lawsuit, recently filed by Ellen Newlin Chase and Margaret Chase Perry, daughters of Edith Newlin, the original author of “Soft Kitty”. Edith wrote the nursery…