View source for Proposals/Stroke position

This is a proposal (based completely on Jérémie Patonnier's mail to www-svg) for a property to control the position of a stroke relative to the path.

<table>
  <tr><th style="text-align: left">Name:</th><th style="text-align: left">stroke-position</th></tr>
  <tr><td>Value:</td><td>middle | inside | outside | &lt;length&gt;</td></tr>
  <tr><td>Initial:</td><td>middle</td></tr>
</table>

The path to be stroked is offsetted by (stroke-width / 2) if "outside" is used, and by -(stroke-width / 2) if "inside" is used.  "middle" is the current behaviour where the middle of the stroke lies on the path.  "0" would be the same as "middle".

== Issues ==

* If implementations simply take the stroke path and offset it, then it's likely you'll get seams between the stroke and the fill of the shape.  Better would be (for "outside") to offset the path edge by stroke-width to get the outer edge of the stroke, and then use the path itself as the inner edge.
* What do percentages resolve against?
* Should we also have a more general shape-offset property that offsets the shape geometry by a certain amount?