Known tinytheme issues

[grantmcdermott]

• Themes do not play nicely with some complex plot types, particularly "spineplot" and "ridge". #297
• Themes dynamic margins could be smarter about titles #303
• Themes do not work well when legend = "top!"
• Should main and sub positions adjust in response to themes with dynamic LHS margin? #479
• Dyanmic themes: axis titles not centered with long perpendicular labels #573
• Themes: axis title resizing via cex.x(y)lab isn't being respected #574