7ef2229 add fixes for 1 bit depth masks

Authored and Committed by caolanm 6 years ago
    add fixes for 1 bit depth masks
    
        Resolves: tdf#104141 CAIRO_FORMAT_A1 vs N1BitLsbPal
        Resolves: tdf#111483 1 bit bitmaps with non-standard black/white indexes
        Resolves: tdf#111073 incorrect gif background color