7321: LayoutFarm.Drawing
7321.1
7368: LayoutFarm.Drawing

not complete
7369: remove dummy classes
7371: LayoutFarm.Drawing.PlatformWinGdi
7379: try more abstract

not complete
7382: more abstraction
7382.1
Merge branch 'v_ab_draw' into v_drawing
7385: LeanBox drawing abstraction

err!
7400: more abstract !
7403: refactor
7404:refactor2
7405: refactor3
7406: Conv Extension method
7407:refactor
Merge branch 'v_ab_draw' into v_drawing
7409: move source code

from LayoutFarm.LeanBox to LayoutFarm.Drawing
7409: refactor
Merge branch 'v_drawing' into v_html_layer