Abbreviations are unreliable

[mattjohnsonpint]

While names work fine, there are several problems with time zone abbreviations returned by this library.

• Following TZNames.GetAbbreviationForTimeZone results in .Standard being null #93
• facing Daylight issue for some countires #90
• GetAbbreviationsForTimeZone returns non abbreviation names. #45
• Incorrect Abbreviation for Atlantic Daylight Time in french (fr-CA) #88
• Both time zone abbreviations for 'Africa/Casablanca' should be WEST #74
• Incorrect Timezone abbreviation for "SA Western Standard Time" #63

And more that have come up without being logged.

In general, there are a few causes:

• CLDR doesn't have abbreviations for every time zone. It has some of them, but they are scattered haphazardly throughout the data. The example in facing Daylight issue for some countires #90 shows how a time zone only has a single daylight abbreviation and no standard or generic abbreviation.
• We could use TZDB abbreviations as a fallback, but we don't. The problem there is that only English abbreviations exists, and in many cases there's just a numeric offset with no abbreviation. Additionally, it's impossible to know which abbreviation or offset should be used generically if the standard and daylight values differ. Even then - we have to resort to only using the current set of values, not historical ones.
• The search algorithm in this library probably could be improved

Ultimately I think the solution is either:

• Find a more reliable source of time zone abbreviation data
• Remove all abbreviations capabilities from this library.