Currently, you can change platform speed, but not enemy speed, which is
always hardcoded to be 4. This commit fixes that, by adding the
"enemyv" property, which is an offset to the speed of 4. Since it
defaults to 0, older levels are not broken by this change.
They were missing the latest strings and also still had strings that
had been deleted.
(Whoever commits the upcoming delivery should also sync that version)
