
The code is suposed to be structured as following:

  utils:     generic support functions
  style:     depends on utils
  gradient:  depends on utils
  path:      depends on style + gradient
  canvas:    depends on path
  surface:   depends on path

The idea is that path drawing should be kept completely independent from
any canvas code. This makes it possible to use path drawing as a tile
element, in a memory surface, or just anywhere else.

The naming convention isn't that precise. Functions and records that have
some kind of generality typically have names Tk_Path* or TkPath*.

This note is mainly written for myself to help remember that I must
try to follow it. Work in progress...

