- Started nghttp2 work

-  Added autoconf config options, temporary for nghttp2 development: `--disable-evhtp`and `--enable-nghttp2`.
- Added special case for api-path:s beginning with //

apps/restconf/restconf_lib.c

@@ -210,6 +210,14 @@ static const map_str2int http_media_map[] = {
     {NULL,                            -1}
 };
 
+/* Mapping to http proto types */
+static const map_str2int http_proto_map[] = {
+    {"http/1.0",  HTTP_10},
+    {"http/1.1",  HTTP_11},
+    {"http/2",    HTTP_2}, 
+    {NULL,        -1}
+};
+
 int
 restconf_err2code(char *tag)
 {
@@ -234,6 +242,18 @@ restconf_media_int2str(restconf_media media)
     return clicon_int2str(http_media_map, media);
 }
 
+int
+restconf_str2proto(char *str)
+{
+    return clicon_str2int(http_proto_map, str);
+}
+
+const char *
+restconf_proto2str(int proto)
+{
+    return clicon_int2str(http_proto_map, proto);
+}
+
 /*! Return media_in from Content-Type, -1 if not found or unrecognized
  * @note media-type syntax does not support parameters
  * @see RFC7231 Sec 3.1.1.1 for media-type syntax type: