RUM 0.1

Fix shameful bug with maximum item size in entry tree

RUM posting trees received rightbound keys.  Accidentally RumMaxItemSize
was corrected according to this.  However RumMaxItemSize is related only
to entry tree which wasn't changed.  That cause long standing bug that long
lexemes can't fit entry tree.  Bug is fixed in this commit.  Also regression
test were added for longest lexemes with longest positions lists.