Microtime Time Zones support

Included in this release:

• Microtime: Now detecting nanoseconds independently of formatting.
• Microtime: Added time zone recognition.
• Microtime: Added the TimeZoneInfo utility class.
• Microtime: Added getTimezoneInfo().
• Microtime: Added getMilliseconds().
• Microtime: Added getNanoseconds().
• Microtime: Added getNanoDate().
• Microtime: Nanoseconds are now persisted when cloning dates.
• Microtime: Time zone identifiers are no longer case sensitive.
• Microtime: getISODate() and getNanoDate() can optionally include the time zone.

Nanoseconds

Microtime will more reliably detect and adjust nanosecond
values in date strings, reducing them to microseconds.
The nanoseconds can still be accessed via getNanoseconds().

Deprecated methods

• Microtime::createFromMicrotime()