MAJOR: 51d: Upgraded to support 51Degrees V3.2 and new features

MAJOR: 51d: Upgraded to support 51Degrees V3.2 and new features

Trie device detection doesn't benefit from caching compared to Pattern.
As such the LRU cache has been removed from the Trie method.

A new fetch  method has been added named 51d.all which uses all the
available HTTP headers for device device detection. The previous 51d
conv method has been changed to 51d.single where one HTTP header,
typically User-Agent, is used for detection. This method is marginally
faster but less accurate.

Three new properties are available with the Pattern method called
Method, Difference and Rank which provide insight into the validity of
the results returned.

A pool of worksets is used to avoid needing to create a new workset for
every request. The workset pool is thread safe ready to support a future
multi threaded version of HAProxy.