Export our gwt-user dependency.
Export our gwt-user dependency.

playn-webgl was previously exporting gwt-user for us, which was indicative of
some confusion. But it also causes issues because projects expect to get
gwt-user from playn-html and since it was two hops away (playn-html ->
playn-webgl -> gwt-user) Maven would prefer any other dependency that exported
a one hop gwt-user depend (e.g. gwt-log -> gwt-user). Those other projects can
and did export an older version of gwt-user which caused probelms.

threerings/playn,threerings/playn,ruslansennov/playn,threerings/playn,ruslansennov/playn,ruslansennov/playn,threerings/playn