Add number for infrastructure manager in <tLine>

The new attribute 'uicNumber', which contains the UIC country code, will be added to complex type 'tLine': <xs:attribute name="uicNumber" type="rail:tTwoDigits" />

For defining the number of the line (without the UIC Country Code), please use the generic attribute 'code'.

The ID of the infrastructure manager will be stored in the new attribute 'imNumber' in complex type 'tLine': <xs:attribute name="imNumber" type="xs:string" />