Treat mailto-URI parameters case-insensitive

RFC 6068 defines these parameters case-insensitive, yet we only
supported lower-case values because the method Uri.getQueryParameters()
treats parameter names case-sensitive.
This patch introduces a wrapper class that implements case-insensitive
parameter name matching.

Note: commit message edited by cketti

src/com/fsck/k9/activity/MessageCompose.java

@@ -3257,7 +3257,8 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
          * creating a new hierarchical dummy Uri object with the query
          * parameters of the original URI.
          */
-        Uri uri = Uri.parse("foo://bar?" + mailtoUri.getEncodedQuery());
+        CaseInsensitiveParamWrapper uri = new CaseInsensitiveParamWrapper(
+                Uri.parse("foo://bar?" + mailtoUri.getEncodedQuery()));
 
         // Read additional recipients from the "to" parameter.
         List<String> to = uri.getQueryParameters("to");
@@ -3291,6 +3292,24 @@ public class MessageCompose extends K9Activity implements OnClickListener, OnFoc
         }
     }
 
+    private static class CaseInsensitiveParamWrapper {
+        private final Uri uri;
+
+        public CaseInsensitiveParamWrapper(Uri uri) {
+            this.uri = uri;
+        }
+
+        public List<String> getQueryParameters(String key) {
+            final List<String> params = new ArrayList<String>();
+            for (String paramName : uri.getQueryParameterNames()) {
+                if (paramName.equalsIgnoreCase(key)) {
+                    params.addAll(uri.getQueryParameters(paramName));
+                }
+            }
+            return params;
+        }
+    }
+
     private class SendMessageTask extends AsyncTask<Void, Void, Void> {
         @Override
         protected Void doInBackground(Void... params) {