Remove eclipse instructions

As sbt-eclipse now works out of the box with scoobi
Implement DList.diff and DList.distinctDiff
Fixing the links in Grouping user guide
DList length elements needs to be using longs
Merge pull request #262 from NICTA/experimental-long

DList length elements needs to be using longs
added the fromLazySeq and lazyObject to create DLists and DObjects from values only evaluated on the cluster
added a simple function to create checkpoints based on BridgeStores. fixes #263
Merge pull request #259 from NICTA/experimental-eclipse

Remove eclipse instructions
Merge pull request #261 from NICTA/experimental-linkfix

Fixing the links in Grouping user guide
merged with pull request #260
fixed the test for #260
fixed the checkpoint specification