Gestion des codes OMR(KERN)/15/en

Calculates and adds the page modulo to the XML file. The code changes on each page. Addition in the XML:

<field name="OMR_mark_page_1">NN</field>
<field name="OMR_mark_page_2">NN</field>
<field name="OMR_mark_page_3">NN</field>
<field name="OMR_mark_page_4">NN</field>