The pingpong logic now uses its own dynbuf for receiving command
response data.
When the "final" response header for a commanad has been received, that
final line is left first in the recvbuf for the protocols to parse at
will. If there is additional data behind the final response line, the
'overflow' counter is indicate how many bytes.
Closes#12757
The threee tags `<name>`, `</name>` and `<command>` were frequently used
with a leading space that this removes. The reason this habbit is so
widespread in testcases is probably that they have been copy and pasted.
Hence, fixing them all now might curb this practice from now on.
Closes#12028
are not, due mainly to the lack of support for XML character entities
(e.g. & => & ). This will make it easier to validate test files using
tools like xmllint, as well as edit and view them using XML tools.
