Nuke renameToPlayN.sh

If, two and a half years down the line, you still haven't
migrated your project, some simple search and replaces on
package names are the least of your worries.
We may have a null stream there.

In particular, it's perfectly legal and common for getErrorStream
to return null.
Nix SHOWN flag, DOM backend no longer existy.
Merge branch 'master' of https://github.com/tomfisher/playn