* Use map[string]struct{} for compression map in Len
map[string]int requires 8 bytes per entry to store the unused position
information.
* Add MsgLength benchmark with more RRs
* Pass dns.Compress explicitly to packBufferWithCompressionMap
* Avoid creating compression map for question only Msg
This idea was inspired by:
"Skip dname compression for replies with no answers."
https://www.nlnetlabs.nl/bugs-script/show_bug.cgi?id=235
* Continue compressing multiple questions
* Fixed len computation when size just goes beyond 14 bits
* Added bouds checks around 14bits
* Len() always right including when around 14bits boudaries
* Avoid splitting into labels when not applicable
* Fixed comments
* Added comments in code
* Added new test cases
* Fixed computation of Len() for SRV and all kind of records
* Fixed Sign that was relying on non-copy for Unit tests
* Removed unused padding
* Fixed typo in PackBuffer() function
* Added comment about packBufferWithCompressionMap() for testing purposes
This offset max was not taking into account leading Len() to emit a
smaller value that could not be matched by Pack(), i.e all names can
be fully compressed or used as a target for compression.
Split length tests off in seperate file length_test.go to clean up
dns_test.og a bit.
Tom Thorogood
Pierre Souchay
Miek Gieben