Column: remove unnecessary interfaces

And propagate Myria-wide
RootOperator: optionally coalesce tuples

Operations like ShuffleProducer or DbInsert may take advantage of this.
ConcatColumn: a column that concatenated two more more existing cols
DbInsert: enable coalescing by default
MyriaConstants: update maximum number of iterations to 1000
eclipse: tweak some formatting settings

Trailing whitespace in Javadocs is here to stay for the time being, however.

http://stackoverflow.com/questions/7008340/eclipse-formatter-adds-space-in-empty-comment-lines
Merge pull request #613 from uwescience/insert-coalesce

WIP coalesce in DbInsert