Added mg_connect(), mg_fetch() API functions. More tests added

mongoose.h

@@ -218,6 +218,26 @@ int mg_get_cookie(const struct mg_connection *,
                   const char *cookie_name, char *buf, size_t buf_len);
 
 
+// Connect to the remote web server.
+// Return:
+//   On success, valid pointer to the new connection
+//   On error, NULL
+struct mg_connection *mg_connect(struct mg_context *ctx,
+                                 const char *host, int port, int use_ssl);
+
+
+// Download given URL to a given file.
+//   url: URL to download
+//   path: file name where to save the data
+//   request_info: pointer to a structure that will hold parsed reply headers
+// Return:
+//   On success, opened file stream to the downloaded contents. The stream
+//   is positioned to the end of the file.
+//   On error, NULL
+FILE *mg_fetch(struct mg_context *ctx, const char *url, const char *path,
+               struct mg_request_info *request_info);
+
+
 // Return Mongoose version.
 const char *mg_version(void);