Fix markup: bogus numerical arguments that were mapped to zero

silently (troff) or under protest (groff); table column width (also
fixed some .L arguments to match actual game output); spacing in
no-fill text; stray .FI, .in and .ce messing up indentation; stray .L;
misspelled request and escape names; escaping of control and escape
characters; properly ignore form-feed; argument quoting; extra
arguments to .NF.  Still broken: .L abused for headings, which
triggers many groff warnings about negative indentation.

info/Commands/path.t

@@ -13,16 +13,17 @@ exactly as for the "route" command:
 .sp
  m/     up-right        (u in level)
  m>     right           (j in level)
- m\\\\     down-right      (n in level)
+ m\e     down-right      (n in level)
 /m      down-left       (b in level)
 <m      left            (g in level)
-\\\\m      up-left         (y in level)
+\em      up-left         (y in level)
 .FI
 .sp
 An example:
 .sp
 .EX path -2,0
 .NF
+.eo
      - - - 0 0 0 0 0 0 0 0 0 0 1 1
      3 2 1 0 1 2 3 4 5 6 7 8 9 0 1
  -5  .   .   a   a   .   .   .   a  -5
@@ -30,11 +31,12 @@ An example:
  -3  a   h   j   a   .   .   +/  .  -3
  -2    ^   a   a   a   .   a/  a    -2
  -1  .   a   a   a   b   +/  +   .  -1
-  0    0\\\\  c   u>  t>  i/  .   .    0
+  0    0\  c   u>  t>  i/  .   .    0
   1  .   a>  l/  ^   a   a   .   .  1
   2    .   a   a   a   .   a   .    2
      - - - 0 0 0 0 0 0 0 0 0 0 1 1
      3 2 1 0 1 2 3 4 5 6 7 8 9 0 1
+.ec
 .FI
 .sp
 where -2,0 distributes to 10,-4 along the path shown.