Type icons are corrupted

[YeldhamDev]

Ubuntu 17.04, Godot Build: 1481a1b

Issue description:
Self-explanatory:

[djrm]

as far as i can tell there are no type icons right now, and probably will not be in a long time, so i would say that the option to enable type icons should be removed until we have all the type icons.

[YeldhamDev]

@djrm Aren't those it?

[djrm]

@YeldhamDev yes, but there are only some of them, not all the types are covered, also i removed those icons since they might need to be redone once the visual shader editor returns.

[reduz]

Type icons option should be removed. I have no idea where this option is. I suggest looking for it (based on the editor settings name), and remove the EDITOR_DEF line.