xF1 Add-on TPU: Add Signature Pictures 1.0.0

Users can upload signature pictures to the forum, which are checked against an admin configurable size and width/height limit.

If users use IMG to link to external images in their signature, the images could be any height, or any filesize which might disrupt other user's browsing experience.

This mod adds 1 field to the xf_user table, uploaded sigs are put in data/sigpics/, similar to how avatars are stored.

Don't forget to enable the permission: Signatures -> Add Signature, to activate this mod for the appropriate user groups.​