Use real terminal window height on Unix when -h0 is passed

When -h0 is passed on the command line, determine the current terminal
window size in runGhcid and use it for output formatting.

Uses the terminal-size package and currently only works on POSIX
systems.
Remove unnecessary import
Only depend on terminal-size package if not on Windows
Merge pull request #16 from kaoskorobase/master

Determine terminal window height automatically on Unix