Added more detail to readme, #136

Not closing 136 until I have thought what to do with scaladoc.
Added InputStream.buffered, closes #121
Added OutputStream.buffered, closes #122
Remove support for null files, closes #140
Merge branch 'master' into 2.9

Conflicts:
	core/src/main/scala/pimpathon/file.scala
	core/src/main/scala/pimpathon/java/io/OutputStream.scala
	core/src/test/scala/pimpathon/java/io/InputStream.scala
	core/src/test/scala/pimpathon/java/io/OutputStream.scala
Added some missing return types
Merge branch 'master' into 2.9