Dealing with highlight lines before filtering lines.

Hi~
I think that when `data-gist-line` attribute and `data-gist-highlight-line` attribute are both provided, the line numbers of highlight lines should be still based on actual code lines(not renumbered line numbers of filtered lines). So I made this commit.
Hope you like it~ :smile: 

Move lines highlight code block before lines filter code block, so that
when lines and highlight lines are both provided the highlight line
numbers are still based on actual code lines(not lines filtered).