[common] debug: add color support to debug messages

People often miss the warnings about invalid arguments in their command
line, this last minute patch attempts to address this by making
warnings, errors, fixme's and fatal errors stand out if stdout is a TTY.

client/src/main.c

@@ -1052,6 +1052,9 @@ static void lg_shutdown(void)
 
 int main(int argc, char * argv[])
 {
+  // initialize for DEBUG_* macros
+  debug_init();
+
   if (getuid() == 0)
   {
     DEBUG_ERROR("Do not run looking glass as root!");