Split out deployment config and get signing plugin to actually work.

Note: required the following in gradle.properties:
signing.keyId=...
signing.secretKeyRingFile=...
signing.password=...
Support native dialog sizing behaviour.

(Sort of, anyway.) Dialogs now use the standard width, but height is
unspecified - this uses 80/100% for landscape/portrait respectively.
Code format.
Add README.
Add gradle release plugin.