Rename Feather icon directory to feather-customised

These icons are based on Feather as the original source, but they have various
tweaks applied, such as stroke width, color, etc. Hopefully the tweaked name
makes this more obvious in the future.

src/components/views/elements/EditableItemList.js

@@ -78,7 +78,7 @@ export class EditableItem extends React.Component {
 
         return (
             <div className="mx_EditableItem">
-                <img src={require("../../../../res/img/feather-icons/cancel.svg")} width={14} height={14}
+                <img src={require("../../../../res/img/feather-customised/cancel.svg")} width={14} height={14}
                      onClick={this._onRemove} className="mx_EditableItem_delete" alt={_t("Remove")} />
                 <span className="mx_EditableItem_item">{this.props.value}</span>
             </div>