dirtometer: Use glib key files for config file
dirtometer: Use glib key files for config file

- Use glib rather than our own parsing code to handle config file

- Use g_file_test() rather than stat() in write_config()

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr