fix: Ctrl-D should distinguish deleting char from quitting
Merge pull request #192 from iwinux/fix-ctrl-d

Proposal: Ctrl-D should distinguish deleting char from quitting
Unicode letters & operators

examples:
let ★ x = x + 5
let (|★) x y = x + y
let summ = ★ 5 |★ 5
comment about \So infix operators