url unescape add check for inconsistent utf8 multibyte parsing

If the url contains special chars (like umlaute äöü) it's interpreted as multybyte char and actually not converted at all (removed).
Added a check if the multibyte convesion is not complete, just add the char as is.

This fixes http://mantis.tokeek.de/view.php?id=200

source/net/yacy/cora/document/id/MultiProtocolURL.java

@@ -565,7 +565,7 @@ public class MultiProtocolURL implements Serializable, Comparable<MultiProtocolU
         return sbuf;
     }
 
-    // from: http://www.w3.org/International/unescape.java
+    // from: http://www.w3.org/International/unescape.java (2015-02-19 !! this eats up characters > 0x80 hex !!)
     public static String unescape(final String s) {
         final int l  = s.length();
         final StringBuilder sbuf = new StringBuilder(l);
@@ -596,6 +596,10 @@ public class MultiProtocolURL implements Serializable, Comparable<MultiProtocolU
                 sumb = (sumb << 6) | (b & 0x3f);    // Add 6 bits to sumb
                 if (--more == 0) sbuf.append((char) sumb); // Add char to sbuf
             } else if ((b & 0x80) == 0x00) {        // 0xxxxxxx (yields 7 bits)
+                if (more > 0) { // 2015-2-19 if this then prev loop was no complete multibyte char (just add it, instead of eating it up)
+                    sbuf.append(s.charAt(i-1));
+                    more = -1;
+                }
                 sbuf.append((char) b);              // Store in sbuf
             } else if ((b & 0xe0) == 0xc0) {        // 110xxxxx (yields 5 bits)
                 sumb = b & 0x1f;