Add configuration variables for multiple days

The number of days displayed in the APP panel has been made
configurable, maximum 21 days, default seven days.

With several days in the APP panel, it may be desirable to "squeeze" the
entries by leaving out the final empty line of each appointment and
lower the number of lines between consecutive days (0, 1, or 2). Both
are made general configuration options. To make a uniform display, an
empty line is added to a day without appointments, if appointments have
an empty line.

Signed-off-by: Lars Henriksen <LarsHenriksen@get2net.dk>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/calcurse.h

@@ -282,6 +282,9 @@ struct conf {
 	enum win default_panel;
 	unsigned compact_panels;
 	unsigned system_dialogs;
+	unsigned multiple_days;
+	unsigned dayseparator;
+	unsigned empty_appt_line;
 	const char *editor;
 	const char *pager;
 	const char *mergetool;