Fix #1181: Support supplementary chars in RuntimeString.
Merge pull request #1270 from sjrd/fix-supplem-chars-in-runtimestring

Fix #1181: Support supplementary chars in RuntimeString.
Fix #974: Implement java.util.UUID.

Except UUID.nameUUIDFromBytes, because that relies on computing
an MD5 or SHA-1 hash.
Fix #1236: Implement java.io.PrintWriter.
Merge pull request #1273 from sjrd/printwriter

Fix #1236: Implement java.io.PrintWriter.
Implement part of java.nio.{Byte,Char}Buffer.

These are required to implement Charset encoders and decoders.
Merge pull request #1274 from sjrd/uuid

Fix #974: Implement java.util.UUID.
Implement the standard Charset encoders and decoders.

* US-ASCII
* ISO-8859-1
* UTF-8
* UTF-16 BE/LE/auto

This also fixes #1087: String.getBytes().
Fix #1263: Implement java.io.InputStreamReader using CharsetsDecoders.
Merge pull request #1259 from sjrd/charsets

Implement the standard Charset encoders and decoders.