Resolve "Config file created by lektord if needed"

Closes #75 (closed)

inc/lektor/config.h

@@ -37,6 +37,9 @@ int config_new(volatile sqlite3 *db, const char *conf);
 /* Prints the default config file. */
 void config_default(FILE *output);
 
+/* Get the default user config file, the ~/.config/lektor/lektor.ini file. */
+void config_default_file(char *dest, size_t len);
+
 /* Manipulate Environment Variables */
 #define env_set(var, val)   setenv(var, val, 1)
 #define env_get             getenv