2227: attempt to remove Correction *

1. try generate correct box at first place
2. introduction to 'new' CssBlockRun!
2228: fix CssLineBox

1. MergeBound()
2. CloseLine()
2229: err!
2231:fix ValidateParentChildRelationship
2234: fixing
2236: temp fix
2237
Merge branch 'v1.7dev' into v1.7