Durations in existing JDK APIs

[Martin Buchholz]

OK, here is a RFR for low-hanging changes (some of these changes have
already been reviewed by some of you):

8204375: Add TimeUnit#convert(Duration)
http://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/convertDuration/index.html
https://bugs.openjdk.java.net/browse/JDK-8204375

8204444: java.time cleanup
http://cr.openjdk.java.net/~martin/webrevs/jdk/time-lint/
https://bugs.openjdk.java.net/browse/JDK-8204444

8204377: Rename Object#wait parameter name from "timeout" to "timeoutMillis"
http://cr.openjdk.java.net/~martin/webrevs/jdk/Object-wait-timeout/
https://bugs.openjdk.java.net/browse/JDK-8204377