Convert core.DomUtils into a static singleton
Convert odf.OdfUtils into a static singleton
Merge pull request #805 from peitschie/statics

Convert two commonly instantiated utils classes into static singletons
Optimize whitespace trimming on paragraph merge

Avoid some unnecessary work by only trimming insignificant whitespace
in the direction of the merge. This is the only place that whitespace
can inadvertently become significant whitespace.