Special folder attributes, even when SPECIAL-USE is not defined

[axoroll7]

In the source code, imapclient check the capability SPECIAL-USE before searching special folder attributes from the output of the command LIST non-extended. But the capability SPECIAL-USE should not be tested when searching special attributes from the non-extended LIST.

While reading the RFC 6154, I come across a line that said the SPECIAL-USE capability is mandatory with the extended LIST command, but not with the non-extended LIST command :

RFC 6154, chapter 2.0, in the first paragraph :
There is no capability string related to the support of special-use attributes on the non-extended LIST command.

With the email provider Zoho mail, folders have special folder attributes, with the output of the command LIST non-extended, but the capability SPECIAL-USE is not present. Zoho mail has a important marked share (maybe 1.58% ?) : Zoho mail market share

When the extended LIST will be implemented, the SPECIAL-USE should should be tested, but only with the extended LIST.

[NicolasLM]

Hello, you seem to be correct. Feel free to submit a PR for that.

[axoroll7]

pull request #533