If pscale is used in scripts with the explicit
PSCALE_ALLOW_NONINTERACTIVE_SHELL env flag, disable the signal changes we do for making the shell work in interactive mode.
This check also needs to verify that all of stdin, stdout & stderr are a proper TTY and not just stdout, since if you pipe in only input for example we still need to disable this since there's no foregrounding.
If pscale is used in scripts with the explicit
PSCALE_ALLOW_NONINTERACTIVE_SHELLenv flag, disable the signal changes we do for making the shell work in interactive mode.This check also needs to verify that all of stdin, stdout & stderr are a proper TTY and not just stdout, since if you pipe in only input for example we still need to disable this since there's no foregrounding.
Fixes #856