Draw polyshape annotations

[lkraav]

Hi @flipbit

I appreciate your work on j-i-a, I found a couple of errors and will be sending a few pull requests.

Re subject: do you have any tips or pointers on what helper tools / libraries to use to get polyshape capability for j-i-a? My primary use case is purely rectangular polyshapes. I envision a UI where perhaps a dot follows mouse on the basic box border and dragging on it will start pulling a connected line away from the rectangle. Then pulling on another dot would drag another line and probably snap the extension box into a rectangle if the line of sight is direct.

Underlying HTML implementation might as well be trusty old imagemap, since it already has all the tools needed to store this info.

I browsed through google maps api which seems to have implemented a lot of this functionality, but I have not been able to discover whether GM API can be used at all outside of a GM application.

I'm not enough of a JS guru yet myself to attack the UI part on my own.