[Enhancement] Don't include bookmark content when searching for tags

[j-krl]

Take this url for example: jonas/tig#26

If I bookmark that url then search for notes with tag vim using nb '#vim', the bookmarked url will be included in the search even with no tags. This is because '#vim' is in the bookmark contents, which shouldn't be included in the search.

[j-krl]

@xwmx am I missing something or should this already be happening in this code? Just did a brief skim of the source but it looks like you have logic that ignores Content and Source sections during search.