The DOUBLE_STATUS_LINES /SET has existed for a long while, but setting it has
never actually had an effect. This change causes it to affect the
/window double setting of new windows: 0 means new windows are created without
double status lines, 1 means only the first window is created with double
status lines and subsequent windows aren't (this is the default) and 2 means
that all windows are created with double status lines.
Note that setting this variable in your .ircrc can't actually affect the first
window, because that's created before the .ircrc is loaded. The compiled-in
default value (DEFAULT_DOUBLE_STATUS_LINES in config.h) is the only thing that
can affect the first window.
Reported by presi.
