Better handling of non-(en-)Windows, non-IANA timezone names

[rfc2822]

Currently, timezones in DTSTART/DTEND which are not

• in the ical4j timezone database (based on IANA timezones, but packaged with ical4j, so in the meanwhile outdated – see Packaged ical4j contains outdated timezones #113),
• an ical4j-known Windows timezone (in msTimezones, see DatePropertyRule)

are converted into UTC (see #163 for a test).

That means that dates and time values can be shifted, which causes problems especially with recurring events, because if the original event is for instance on "Friday 23:00 Special_Timezone (and repeating every Friday)", it can become "Saturday 01:00 UTC (and repeating every Friday)", which breaks the recurrence.

Suggested solution

TZID replacement should be done more carefully:

1. If a TZID is a known (English) Windows TZID, replace it by IANA TZID.
2. If a TZID is a known localized Windows TZID, replace it by IANA TZID.
3. If a TZID is another unknown TZID, try to replace it (in this order):
   1. by the first known timezone with the same (current? at DTSTART?) DAYLIGHT and STANDARD offset,
   2. or by the system default timezone.