SPARK-1057 (alternative) Remove fastutil

(This is for discussion at this point -- I'm not suggesting this should be committed.)

This is what removing fastutil looks like. Much of it is straightforward, like using `java.io` buffered stream classes, and Guava for murmurhash3.

Uses of the `FastByteArrayOutputStream` were a little trickier. In only one case though do I think the change to use `java.io` actually entails an extra array copy.

The rest is using `OpenHashMap` and `OpenHashSet`.  These are now written in terms of more scala-like operations.

`OpenHashMap` is where I made three non-trivial changes to make it work, and they need review:

- It is no longer private
- The key must be a `ClassTag`
- Unless a lot of other code changes, the key type can't enforce being a supertype of `Null`

It all works and tests pass, and I think there is reason to believe it's OK from a speed perspective.

But what about those last changes?

Author: Sean Owen <sowen@cloudera.com>

Closes #266 from srowen/SPARK-1057-alternate and squashes the following commits:

2601129 [Sean Owen] Fix Map return type error not previously caught
ec65502 [Sean Owen] Updates from matei's review
00bc81e [Sean Owen] Remove use of fastutil and replace with use of java.io, spark.util and Guava classes

1 files changed, 0 insertions, 5 deletions

diff --git a/pom.xml b/pom.xml
index c03bb35c99..5f66cbe768 100644
--- a/pom.xml
+++ b/pom.xml
@@ -349,11 +349,6 @@
         </exclusions>
       </dependency>
       <dependency>
-        <groupId>it.unimi.dsi</groupId>
-        <artifactId>fastutil</artifactId>
-        <version>6.4.4</version>
-      </dependency>
-      <dependency>
         <groupId>colt</groupId>
         <artifactId>colt</artifactId>
         <version>1.2.0</version>