Allow nested ranges without header row and service row

[yohny]

Currently when creating nested (master+detail) tables the parent range need to contain its child range completely, which makes sense, but in addition to this parent range also needs to contain at least one more row above its child range and one row below its child range, otherwise exception is thrown. It would be nice if those would not be required to support usecases where you want to create nested tables without header or service rows.