Set version number to 21.0

Set version number to 21.0-rc2

Set version number to 21.0-rc1

Update version numbers to 20.0.

Set version numbers to 20.0-rc1.

Set release version numbers to 19.0

Set release version numbers to 19.0-rc3

Set release version numbers to 19.0-rc2

Set release version numbers to 19.0-rc1

Fix a few calls to String.getBytes(Charset), which didn't exist in JDK5.