Fix image on footer problems

If you put images on footer, when you create multiple pages pdf, in all pages but last, the images are often printed rotated and with wrong dimensions.
This is because we have a PageBreakTrigger that involves the inner content, but we should avoid this operations on footer images that are not involved in page break and should by printed in the same way in first, inner and last pages.

Author: piciuriello

tcpdf.php

@@ -6925,8 +6925,8 @@ protected function fitBlock($w, $h, $x, $y, $fitonpage=false) {
 			// fallback to avoid division by zero
 			$h = $h == 0 ? 1 : $h;
 			$ratio_wh = ($w / $h);
-			if (($y + $h) > $this->PageBreakTrigger) {
-				$h = $this->PageBreakTrigger - $y;
+			if (($y + $h) > $this->PageBreakTrigger + $this->bMargin) {
+				$h = $this->PageBreakTrigger + $this->bMargin - $y;
 				$w = ($h * $ratio_wh);
 			}
 			if ((!$this->rtl) AND (($x + $w) > ($this->w - $this->rMargin))) {