Detect and remove secondary rows

[heijul]

Currently, secondary rows* are detected and removed only for Days. We should do something similar for the RouteAnnot and AnnotEntry types.
Alternatively, we can assume, that a secondary Days row is simply the start of the next table and every field below that row (including the row, of course) will have its type set to Other.

• i.e. rows containing fields of a type, that succeed a row containing fields of the sametype.