Recognize case-insensitive properties

Fixes #1204 ; Closes #1205

bits/22_xmlutils.js

@@ -21,11 +21,13 @@ function parsexmltag(tag/*:string*/, skip_root/*:?boolean*/)/*:any*/ {
 		if(j===q.length) {
 			if(q.indexOf("_") > 0) q = q.slice(0, q.indexOf("_")); // from ods
 			z[q] = v;
+			z[q.toLowerCase()] = v;
 		}
 		else {
 			var k = (j===5 && q.slice(0,5)==="xmlns"?"xmlns":"")+q.slice(j+1);
 			if(z[k] && q.slice(j-3,j) == "ext") continue; // from ods
 			z[k] = v;
+			z[k.toLowerCase()] = v;
 		}
 	}
 	return z;

xlsx.flow.js

@@ -2224,11 +2224,13 @@ function parsexmltag(tag/*:string*/, skip_root/*:?boolean*/)/*:any*/ {
 		if(j===q.length) {
 			if(q.indexOf("_") > 0) q = q.slice(0, q.indexOf("_")); // from ods
 			z[q] = v;
+			z[q.toLowerCase()] = v;
 		}
 		else {
 			var k = (j===5 && q.slice(0,5)==="xmlns"?"xmlns":"")+q.slice(j+1);
 			if(z[k] && q.slice(j-3,j) == "ext") continue; // from ods
 			z[k] = v;
+			z[k.toLowerCase()] = v;
 		}
 	}
 	return z;