Added a new method to crosstab group that allows to set total header stretchWithOverflow attribute

git-svn-id: http://svn.code.sf.net/p/dynamicreports/code/trunk@752 bf0c503b-2351-4f66-9eae-aa52f3279a3f
Added new test methods

git-svn-id: http://svn.code.sf.net/p/dynamicreports/code/trunk@753 bf0c503b-2351-4f66-9eae-aa52f3279a3f
new crosstab junit test

git-svn-id: http://svn.code.sf.net/p/dynamicreports/code/trunk@754 bf0c503b-2351-4f66-9eae-aa52f3279a3f