WISH: dashed lines in DRAW

[meijeru]

As requested (see Red repo issue 5540) here is a proposal in the form of an extra paragraph in draw.adoc. Note that the original wording was for a "dotted" line pattern. It is felt that the term "dashed" is more appropriate.

2.13.x. Dashed pen

  Syntax

  pen dashed <color1> <size1> <color2> <size2>

  <color1> : (optional) color of the dashes (tuple! word!)
  <color2> : (optional) color of the gaps   (tuple! word!)
  <size1>  : (optional) size of each dash in pixels or fraction of the length (integer! percent!).
  <size2>  : (optional) size of each gap  in pixels or fraction of the length (integer! percent!).

  Description

  Sets a dash pattern to be used for drawing operations.
  The defaults for color1 and color2 are black and transparent.
  The defaults for size1 and size2 are 5%.