added file extension commands

defines.h

@@ -71,6 +71,10 @@ typedef struct Mimetype {
 	char *mimetype;
 	char *command; 
 } mimetype;
+typedef struct Extension {
+	char *file_extension;
+	char *command; 
+} extension;
 typedef struct Binding {
 	char* key;
 	void (*func)();