Declare foreground and background variables global

Removes the need to pass the terminal's default background color round.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/vars.c

@@ -48,6 +48,9 @@ int resize = 0;
 /* variable to tell if the terminal supports color */
 unsigned colorize = 0;
 
+/* Default background and foreground colors. */
+int foreground, background;
+
 /*
  * To tell if curses interface was launched already or not (in that case
  * calcurse is running in command-line mode).