Removed the 900 penalty mechanism which anyway almost always produced visually bad...

Removed the 900 penalty mechanism which anyway almost always produced visually bad results. Now the first step for a row is computed so that each cell starting on it can contribute some content.
Used a similar mechanism to replace backtracking: the current row is now allowed to grow as long as there is not enough space on the current page to make the next row fit. The next row is "delayed", so this mechanism is called "row-delaying"

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@619854 13f79535-47bb-0310-9956-ffa450edef68