terminal size is not correctly reported on windows

[prabirshrestha]

Apparently in Windows in cmd the terminal size is not correctly reported.

In win32 apis there are two sizes - one for window and one for the buffer. Currently it reports the buffer size instead of the window size. So if set the buffer height/lines to 9999, that is the value it returns instead of the window height which is lot smaller.

Seems like need to do a bit more calculation. https://stackoverflow.com/a/12642749

This is not an issue with the new windows terminal, only issue with the cmd.exe.

[murarth]

@prabirshrestha Thank you for filing this issue. I've submitted PR #15 to address it. Can you confirm that it gives the correct result?