Examples throw ClassNotFoundException without fork in run

[nevillelyh]

sbt/sbt#3736

Adding fork in run := true fixes it but introduces other annoyance, e.g. stdout treated as error and relative path README.md in word count quick start not working.

[error] Caused by: java.lang.ClassNotFoundException: scala.Function0
[error]         at sbt.internal.inc.classpath.ClasspathFilter.loadClass(ClassLoaders.scala:74)
[error]         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
[error]         at java.lang.Class.forName0(Native Method)
[error]         at java.lang.Class.forName(Class.java:348)
[error]         at com.twitter.chill.KryoBase$$anonfun$1.apply(KryoBase.scala:41)
[error]         at com.twitter.chill.KryoBase$$anonfun$1.apply(KryoBase.scala:41)

[ravwojdyla]

Should be fixed by sbt/zinc#473