Expand all leading tabs in markdown files

Given how problematic leading tabs in markdown files can be,
we have expanded all leading tabs in markdown files by:

```sh
find * -type f -name '*.md' -print |
  while read -r file; do
    rm -f "$file.tmp" ;
    expand < "$file" > "$file.tmp" ;
    mv -f -v "$file.tmp" "$file" ;
  done
```

Given the previous changes to `bin/pandoc-wrapper.sh` and other recent
commits and recent pull requests, the were were **NO** changes to
any HTML files.  This is a **good thing** as the expression goes.

No there are no leading tabs in any markdown files.
A check to catch any re-introduction of leading tabs
into any markdown file is on the way.

BTW: We do not have anything against leading tabs in files,
even though we have had to deal with their impact on forming
HTML from markdown files (as well as the calc source code).
It is just that this is one of those cases where tabs conflict
(sometimes caused by people wanting to change the classic
8-space tab model) with a desired outcome.

Perform `make www` to perform the above and test under macOS.

2020/ferguson1/terminals.md

@@ -8,13 +8,13 @@ sanity if it causes any problems) as well as colours (limitations etc.).
 <div id="toc">
 -   [Capabilities support testing program](#termcaps)
 -   [Setting the game dimensions](#dimensions)
-    *	[The LINES and COLUMNS environmental variables](#linescolumns)
-    *	[Terminal insanity](#insanity)
-    *	[Restoring the terminal](#restore)
-    *	[Terminal size abuse](#abuse)
+    *   [The LINES and COLUMNS environmental variables](#linescolumns)
+    *   [Terminal insanity](#insanity)
+    *   [Restoring the terminal](#restore)
+    *   [Terminal size abuse](#abuse)
 -   [Terminal limitations](#termlimitations)
 -   [Terminal colours](#colours)
-    *	[Curses background](#background)
+    *   [Curses background](#background)
     *   [Monochrome terminals](#monochrome)
     *   [Colour limitations](#colourlimitations)
     *   [Disabling colour](#disablecolour)
@@ -49,7 +49,7 @@ This compiles the program [termcaps.c](%%REPO_URL%%/2020/ferguson1/termcaps.c) a
     terminal cols 155 (153 playable)
 
     snake size:   997 (max size: 5776)
-	  bugs:   199 (max size: 1155)
+          bugs:   199 (max size: 1155)
 
     at least 34 columns (currently 155) recommended for snake size 997
     at least 37 columns (currently 155) recommended for capped snake size 5776
@@ -79,7 +79,7 @@ example:
     terminal cols 155 (153 playable)
 
     snake size:  5776 (max size: 5776)
-	  bugs:  5771 (max size: 5771)
+          bugs:  5771 (max size: 5771)
 
     at least 37 columns (currently 155) recommended for snake size 5776
     at least 37 columns (currently 155) recommended for capped snake size 5776
@@ -153,7 +153,7 @@ Say you want 55 columns:
 This will force curses to detect the max columns (X) of your terminal (for the
 game dimensions) - to be 55; it might look like this instead:
 
-	    X:27/54 Y:20/41 S:5/997 B:0
+            X:27/54 Y:20/41 S:5/997 B:0
 
 But problems can arise with messing with dimensions: in my tests this held only
 to lines.
@@ -194,10 +194,10 @@ The Linux man page says:
 ```
     You might have to run the `reset` tool like:
 
-		   <LF>reset<LF>
+                   <LF>reset<LF>
 
-	       (the line-feed character is normally control-J) to get the terminal
-	       to work, as carriage-return may no longer work in the abnormal state.
+               (the line-feed character is normally control-J) to get the terminal
+               to work, as carriage-return may no longer work in the abnormal state.
 ```
 
 If you don't have the reset utility you can try:
@@ -320,7 +320,7 @@ The manpage for `init_pair()` says this:
 
     [...]
 
-	COLOR_PAIRS corresponds to the terminal database's max_pairs capability, (see terminfo(5)).
+        COLOR_PAIRS corresponds to the terminal database's max_pairs capability, (see terminfo(5)).
 ```
 
 Based on the two as well as the fact that monochrome terminals (I've tried under
@@ -332,11 +332,11 @@ confirm this I wrote the following code with the output below:
 
     int main()
     {
-	initscr();
-	start_color();
-	printw("COLORS: %d\nCOLOR_PAIRS: %d\n", COLORS, COLOR_PAIRS);
-	getch();
-	endwin();
+        initscr();
+        start_color();
+        printw("COLORS: %d\nCOLOR_PAIRS: %d\n", COLORS, COLOR_PAIRS);
+        getch();
+        endwin();
     }
 ```
 
@@ -361,17 +361,17 @@ number is out of the range? To try and figure this out I did another test:
 ``` <!---c-->
     int main()
     {
-	initscr();
-	start_color();
+        initscr();
+        start_color();
 
-	init_pair(COLOR_PAIRS+1, COLOR_WHITE, COLOR_GREEN);
-	bkgd(COLOR_PAIR(COLOR_PAIRS+1));
-	init_pair(1, COLOR_WHITE, COLOR_BLACK);
-	attron(COLOR_PAIR(1));
-	printw("COLORS: %d\nCOLOR_PAIRS: %d\n", COLORS, COLOR_PAIRS);
+        init_pair(COLOR_PAIRS+1, COLOR_WHITE, COLOR_GREEN);
+        bkgd(COLOR_PAIR(COLOR_PAIRS+1));
+        init_pair(1, COLOR_WHITE, COLOR_BLACK);
+        attron(COLOR_PAIR(1));
+        printw("COLORS: %d\nCOLOR_PAIRS: %d\n", COLORS, COLOR_PAIRS);
 
-	getch();
-	endwin();
+        getch();
+        endwin();
     }
 ```