Arrange Synced Highlights in Order of Appearance in Document

[isosphere]

At present, highlights are synced in as they are found in the metadata file. However, this may or may not be sorted. The user may add a highlight earlier in a document they've already read, but we'll add it to the end of their bookmarks when syncing.

Our current syncing is probably chronological, though not necessarily guaranteed to be. I think we should guarantee positional sorting: the first highlight in a document should be the first block under the "Bookmarks" heading, etc.