Occasional uglifying

[listvin]

1. I really don't want effect on code blocks with syntax highlighted. Example in readme.

2. I also don't want bolding in unhiglhted code blocks (code naturally has a lot of (){<}>=::@ stuff for eye catching), tho I do understand they may be harder to detect.

3. I do want bolding in <pre> blocks with plain text on human languages.

4. Probably because some sites don't have loaded bold versions of font, your bold spans fallback to some other font. As a result, the page becomes a ransom note carved from newspapers, which does not help reading much. Non-latin fonts seem more vulnerable. Unfortunately I do not have specific examples in mind and I can't find them, because I am too frustrated with Perfomance issues on big page load or config change #15 and have to stop using sR for a while((((