miniterm: restore EOL and repr toggles, rename transformation->filter
miniterm: restore EOL and repr toggles, rename transformation->filter

- EOL mode can be toggled (menu + CTRL+L)
- filters can be edited at runtime (menu + CTRL+F)
- encoding can be changed at runtime (menu + CTRL+A)


DavidHowlett/pyserial-1,hoihu/pyserial