Quit issues

[fanfani]

all programs should have one or more ways to quit, e.g.

• trap ctrl+c

• user specified time of execution

• when relevant (e.g. snake, text), user specified "game rounds" before exit

[fanfani]

just found out that hitting "Esc" does actually quit all programs.

still, it is convenient to have all other options implemented, including ctrl+c