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.