Hot on the heels of #74, I'm stirring up text rendering yet again.

Namely, I've removed FontCacheType entirely. It was something of an implementation detail that had poked its head out and now it's gone. Font objects are really just basic descriptions of a font to be loaded when rendering text; they aren't concerned with how they're cached now.

FontCacheType was up until now the way to control if text was rendered in raster mode or vector mode. That decision is now captured by the TextDrawingMode.TextDrawRaster enumeration value which is also the default value for GraphicsState.text_drawing_mode. TextDrawRaster is the only text drawing mode which uses the raster rendering path; all other modes use the slower [but much more powerful] vector rendering path.

Another breaking change is that the canvas draw_text method now uses the fill paint instead of the stroke paint when drawing in raster mode. If all of your colored text turns black after this change, that's the reason.