The 3D text object should accept html text

[BruceSherwood]

html text is acceptable in canvas title and caption, and in label objects. It should also be acceptable for the 3D text object. For ideas, see the label function in lib/glow/primitives.js, which calls the parse_html function located in lib/glow/api_misc.js, which handles bold (or strong), italic, (or em) sup, and sub. The main text code is in lib/glow/extrude.js, with the actual text function in lib/glow/primitives.js.