Simplify Windows to/from IANA conversion methods

[GoogleCodeExporter]

What situation does this request make simpler?
Since Noda Time contains IANA, Windows, and CLDR data, it can be used to 
convert BCL time zones to or from TZDB time zones.  The data is exposed in the 
API, but sensible conversion methods aren't included.  This could be more 
convenient, such as illustrated here:
http://stackoverflow.com/a/17348822/634824

Can you provide a straw-man example of what you'd want the API to look
like?

string bclZoneId = 
TzdbDateTimeZoneSource.Default.WindowsMapping.TranslateToBcl(tzdbZoneId);

string tzdbZoneId = 
TzdbDateTimeZoneSource.Default.WindowsMapping.TranslateToTzdb(bclZoneId);


We could also consider (in addition) a new method to DateTimeZone with the 
signature:

public DateTimeZone TranslateFor(IDateTimeZoneProvider provider)

Which would give some convenience for those not used to calling into a the 
TzdbDateTimeSource, for example:

DateTimeZone bclZone = 
DateTimeZoneProviders.Tzdb[tzdbZoneId].TranslateFor(DateTimeZoneProviders.Bcl);

DateTimeZone tzdbZone = 
DateTimeZoneProviders.Bcl[bclZoneId].TranslateFor(DateTimeZoneProviders.Tzdb);

Original issue reported on code.google.com by mj1856 on 26 Mar 2014 at 6:08

[jskeet]

We can add these later - it shouldn't block 2.0.

[jskeet]

Time to finally do this, I think. Let's start with just the TranslateToBcl and TranslateToTzdb methods - things get really complicated if you put them on DateTimeZone, which doesn't currently know its source.