According to RFC 5545, iCalendar content lines can have optional
parameters, which can be quoted strings containing colons (":"). Make
sure that such colons are not interpreted as delimiters marking the
start of the value string.
Also, add a test case that covers this corner case.
Reported-by: Håkan Jerning <jerning@home.se>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>
