Conditionally skip calls to jedi_vim.show_call_signatures
Conditionally skip calls to jedi_vim.show_call_signatures

Skip calls to `jedi_vim.show_call_signatures` if the (position of the) current
function's argument did not change (by means of comma positions before
and after the cursor).

Ref: https://github.com/davidhalter/jedi-vim/pull/420

FBruynbroeck/jedi-vim,davidhalter/jedi-vim,genzj/jedi-vim