Support import of time zones (RFC 5545)

The property parameter time zone identifier (TZID) is recognized in DTSTART,
DTEND and EXDATE and the DATE-TIME value converted to a local time. The time
zone identifier is logged in the note file.

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

test/ical-007.sh

@@ -8,16 +8,20 @@ if [ "$1" = 'actual' ]; then
   TZ="America/New_York" "$CALCURSE" -D "$PWD/.calcurse" \
     -i "$DATA_DIR/ical-007.ical"
   "$CALCURSE" -D "$PWD/.calcurse" -s02/23/2015
+  cat "$PWD/.calcurse/notes/"*
   rm -rf .calcurse || exit 1
 elif [ "$1" = 'expected' ]; then
   cat <<EOD
-Import process report: 0013 lines read
-2 apps / 0 events / 0 todos / 0 skipped
+Import process report: 0018 lines read
+3 apps / 0 events / 0 todos / 0 skipped
 02/23/15:
+ - 05:00 -> 06:00
+	CET
  - 06:00 -> 07:00
 	UTC
  - 11:00 -> 12:00
 	Local time
+Import: TZID=CET
 EOD
 else
   ./run-test "$0"