sm-selection: shrink method on Y.Range

shrinks (normalizes?) the range start/end containers to the textnodes that contain the selected text.
build gallery-sm-range
gallery-sm-editor: new editor-style extension for css based editing
build gallery-sm-editor
gallery-sm-selection: use options hash instead of boolean for trim argument to Y.Range shrink* methods
gallery-sm-selection: don't pummel the offset if not changing nodes
build gallery-sm-selection, gallery-sm-editor
Merge pull request #23 from bwg/editor-style

Editor-style for css based editing