javascript functions for translating from game map coordinates to html element display coordinates

[jrwarwick]

javascript functions to convert from game map coordinates (as presented in server libraries like IAN) to the cartography.html map dom element display. The map is auto-resizing based on screensize so that may present some extra challenge.

Once coordinate mapping is covered, some functions to either (a) create a canvas "overlay" and plot dots at arbitrary (game) coordinates, or (b) place div elements at arbitrary (game) coordinates.