Drop legacy online help system

Remove the old online help system and change the generic help key to do
the same thing as ":help".

This also removes some context-sensitive help. We should think about
re-adding support for this later.

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

src/Makefile.am

@@ -19,7 +19,6 @@ calcurse_SOURCES = \
 	day.c \
 	event.c \
 	getstring.c \
-	help.c \
 	ical.c \
 	io.c \
 	keys.c \