Changed Cut/Copy/Paste assets.

New assets, in dark/light version.

Made public attributes of the Theme, so that they can be customized.

Select_all was not included in that change. It is supposed to be represented
as text instead of an icon. Waiting for a CL that enables this feature.

Change-Id: Icc912b2eb582295c60c0a409760d2c3d65989fc6