(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
Currently, graphs are defined in terms of graph color. This means that
when the system palette is changed, the old colors are still used. We
switch to storing the color roles and looking up the palette colors on
paint events. We also define the graph line background color as the
graph color at half-transparency.
