Implement sending content from progmem

make the example editor run from progmem

src/WebResponses.cpp

@@ -471,6 +471,27 @@ size_t AsyncChunkedResponse::_fillBuffer(uint8_t *data, size_t len){
   return _content(data, len, _sentLength);
 }
 
+/*
+ * Progmem Response
+ * */
+
+AsyncProgmemResponse::AsyncProgmemResponse(int code, String contentType, const uint8_t * content, size_t len){
+  _code = code;
+  _content = content;
+  _contentType = contentType;
+  _contentLength = len;
+}
+
+size_t AsyncProgmemResponse::_fillBuffer(uint8_t *data, size_t len){
+  size_t left = _contentLength - _sentLength;
+    if (left > len) {
+      memcpy_P(data, _content + _sentLength, len);
+      return len;
+    }
+    memcpy_P(data, _content + _sentLength, left);
+    return left;
+}
+
 
 /*
  * Response Stream (You can print/write/printf to it, up to the contentLen bytes)