add Line2D style property

Change-Id: I72d9426b6910205645bae2828ef14aaabad138c3
use UNO constants instead of magic numbers

Change-Id: I7a38518783e57d3230301f94bf0831a73670385f
Rectangle transparence gradient

Change-Id: Ibca7039eee1c48d487928822e5a01455a07351fd
a bit more clean-up in the chart2 OpenGL code

Change-Id: I0c30a9c8e2a9e0f199308523bbc5fc76c94307c7