Change termcap to sgr0 for resetting terminal colors - fixes tput warning

[smartmic]

I got this warning from tput everytime I run kanban

tput: unknown terminfo capability 'normal'

The tput command within the trap has a weird syntax which is not correct (at least as I am aware of). I could not find any reference where, after the terminal capability, two dashes signal the end of cli options, followed by "normal". Could this be a copy & paste error?

Anyhow, my fix seems to work fine. Also, I changed the capability from cnorm to sgr0 which seems more appropriate for resetting the terminal colors.

[coderofsalvation]

I will test this asap. Could be a nice improvement compared to https://github.com/coderofsalvation/kanban.bash/pull/33