Exclude undesired resize parameters in tile server
Don't highlight unloaded images

It looks like FF gives empty images a size of 36x36, so this is one
piece of the puzzle
Fix on-load semantics

.load is deprecated, and seemed to give me intermittent issues (though
I'm not sure if something else may have been going on at the time, so
this could be totally unrelated)
Don't double-highlight thumbnails
Fix offset for highlighting
Account for unusually tall or wide images

Max dimension is 200 per div style rules, so an image that's got more
than a 2:1 ratio would break the prior JS check
Merge branch 'feature/fix-highlighting'
Make anti-DOS path less static

Allows us to change thumbnail and medium image sizes within a much
broader range (100 - 699)