Clean up and new streaming script check-mode feature.

[new] The stream.py streaming script now has a check-mode option, where it will place Grbl in $C check mode automatically and then stream the g-code program. It's a very fast way to check if the g-code program has any errors.

[fix] The debug variable was not initialized if the debug option was enabled in config.h

[fix] Updated error_codes CSV file to the same format as the others.

doc/log/commit_log_v1.1.txt

@@ -1,3 +1,22 @@
+----------------
+Date: 2017-05-31
+Author: chamnit
+Subject: New nonlinear spindle speed PWM output model and solution. Updated scripts.
+
+[new] A nonlinear spindle speed/PWM output option via a piecewise
+linear fit model. Enabled through config.h and solved by a Python
+script in /doc/script
+
+[new] fit_nonlinear_spindle.py. A solver script that can be run on
+http://repl.it for free. No Python install necessary. All instructions
+are available in the script file comments.
+
+[new] stream.py has been updated to include status reports feedback at
+1 second interval.
+
+[fix] stream.py bug fix with verbose mode disabled.
+
+
 ----------------
 Date: 2017-03-24
 Author: Sonny Jeon