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
... as this is already done much earlier in the URL parser.
Also add test case 894 that verifies that pop3 with an encodedd CR in
the user name is rejected.
Closes#4887