Fix JPEG spec references per ISO/ITU-T suggestions

- When referring to specific clauses, annexes, tables, and figures, a
  "timed reference" (a reference that includes the year) must be used in
  order to avoid confusion.
- "CCITT" = "ITU-T"
- Replace ambiguous "JPEG spec" with the specific document number.

jmorecfg.h

@@ -5,7 +5,7 @@
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * Modified 1997-2009 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2009, 2011, 2014-2015, D. R. Commander.
+ * Copyright (C) 2009, 2011, 2014-2015, 2018, D. R. Commander.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -17,9 +17,9 @@
 
 /*
  * Maximum number of components (color channels) allowed in JPEG image.
- * To meet the letter of the JPEG spec, set this to 255.  However, darn
- * few applications need more than 4 channels (maybe 5 for CMYK + alpha
- * mask).  We recommend 10 as a reasonable compromise; use 4 if you are
+ * To meet the letter of Rec. ITU-T T.81 | ISO/IEC 10918-1, set this to 255.
+ * However, darn few applications need more than 4 channels (maybe 5 for CMYK +
+ * alpha mask).  We recommend 10 as a reasonable compromise; use 4 if you are
  * really short on memory.  (Each allowed component costs a hundred or so
  * bytes of storage, whether actually used in an image or not.)
  */