Overhaul

Changed into IIFE, changed around functions, updated comments, better
code conventions
Deprecated stripBRs

Was only in use by discover-feeds module, so now it is only defined in
that module
Improve tracer image detection

Was not always detecting some 1px images, improved the set of conditions
that can match
Use new queryGoogleFeeds function

After refactoring discoverFeeds module, use the new function. Basically
a diff name with reordered params in a diff namespace.
Misc

Improved collectTextNodeLengths function, added some more blacklisted
axes, deleted a redundant declaration of forEach