TZInfo provides daylight savings aware transformations between times in
different timezones.

Data Sources
------------

TZInfo requires a source of timezone data. There are two built-in options:

1. The TZInfo::Data library (the tzinfo-data gem). TZInfo::Data contains a set 
   of Ruby modules that are generated from the [IANA Time Zone Database](http://www.iana.org/time-zones).
2. A zoneinfo directory. Most Unix-like systems include a zoneinfo directory 
   containing timezone definitions. These are also generated from the 
   [IANA Time Zone Database](http://www.iana.org/time-zones).

By default, TZInfo::Data will be used. If TZInfo::Data is not available (i.e. 
if `require 'tzinfo/data'` fails), then TZInfo will search for a zoneinfo
directory instead (using the search path specified by 
`TZInfo::ZoneinfoDataSource::DEFAULT_SEARCH_PATH`).

If no data source can be found, a `TZInfo::DataSourceNotFound` exception will be
raised when TZInfo is used. Further information is available 
[in the wiki](http://tzinfo.github.io/datasourcenotfound) to help with 
resolving `TZInfo::DataSourceNotFound` errors.

The default data source selection can be overridden using 
`TZInfo::DataSource.set`.

Custom data sources can also be used. See `TZInfo::DataSource.set` for
further details.