[Issue #9] [Issue #10]  Fixed cell_props applied to a different row when 'Repeat Headers' is enabled
Other changes in this commit:
1. Introduced column_numbers variable to avoid using $record in a broader scope. Furher improvement needed.
2. Header row height is copied to each new page when 'Repeat Headers' is enabled
3. Fixed messing up row height when repeat headers is enabled due to access by array index vs shift/unshift
4. Fixed row height for rows with text blocks