Cleanup and improve source code comments

Global review, which includes the following changes to try to increase
consistency, update and improve the source code comments:

 - Spelling fixes.
 - Use American English forms.
 - Uppercase NULL, NUL and ASCII.
 - Use “Note: ” instead of the slightly cryptic “NB: ” form.
 - Write comments as proper sentences, including capitalizations and
   ending dots.
 - Move comments before the code, function or variable they refer to.
 - Move general function comments outside the body.
 - Convert function and variable description comments to doxygen.
 - Use one space before dot, exclamation and question marks.
 - Use ‘’ or “” instead of `' style quoting.
 - Remove author names from comments, already visible from “git blame”.
 - Mark strings for translators with “TRANSLATORS: ”.
 - Remove useless or outdated comments.
 - Fix comment indentation.
 - Standardize comment format:

   /* Short text comment. */

   /* Long text,
    * comment. */

   /*
    * Section text.
    */

1 files changed, 5 insertions, 4 deletions

diff --git a/dselect/pkgdisplay.cc b/dselect/pkgdisplay.cc
index 13ad3268c..06512d17c 100644
--- a/dselect/pkgdisplay.cc
+++ b/dselect/pkgdisplay.cc
@@ -39,10 +39,11 @@ const char
 			    N_("remove"), 
 			    N_("purge"),
 			    0 },
-/* WTA: the space is a trick to work around gettext which uses the empty
- * string to store information about the translation. DO NOT CHANGE
- * THAT IN A TRANSLATION! The code really relies on that being a single space.
- */
+
+  /* TRANSLATORS: The space is a trick to work around gettext which uses
+   * the empty string to store information about the translation. DO NOT
+   * CHANGE THAT IN A TRANSLATION! The code really relies on that being
+   * a single space. */
   *const eflagstrings[]=   { N_(" "), 
 			     N_("REINSTALL"), 
 			     0 },