Complete vector drawing UI instructions set

Pliant provides a very good vector drawing instructions set (few instructions, but enough to cover most PDF capabilities).
These instructions are:






See /pliant/graphic/draw/prototype.pli for details.

At the moment, only 'fill' instruction can be used at UI application level.

the glue code bringing access to other instructions has to be provided.

one more instruction will be needed to enable to define a rectangle area (potentially rotated) that will contain positioning instructions (paragraphs) as opposed to vector instructions.

we need to define how much of the advanced Pliant color management (and transparency handling) is to be exposed at UI application level.

'draw' instruction probably needs to be replaced by 'draw_define' 'draw_write' and 'draw_inline' to enable using the same drawing several times, just like images.

no store drawing has to be provided (the UI client does not store the display list, but requests it from the server each time some part has to be redrawn). It has to be sub display lists, and the UI client can cache them on disk anyway.

drawings should be usable for providing advanced fonts capabilities (a complex problem here is: does an advanced character just ignores the font color parameter, or use it through a shading gamut, or should we introduce multiple font color parameters)