Fix some formatting errors, typos and other problems (#78)

Some notes:
- Removed a TODO note that was fixed in commit 43d9fbac.
- Removed a duplicate note about the '%l' time format in the changelog.
- Applied the following documentation fixes from Terrence J. Doyle:
  - https://www.mail-archive.com/ast-developers@lists.research.att.com/msg01852.html
  - https://www.mail-archive.com/ast-developers@lists.research.att.com/msg01856.html
- Fixed strange grammar in one of the error messages.
- Added missing options for rksh to the synopsis section.
- Applied a formatting fix from ksh93v- to the man page.
- Replaced a C99 line comment in src/lib/libast/comp/realpath.c with a
  proper comment that is valid in C89.
- Prioritize UTC over GMT in the documentation (missed by commit c9634e90).
- Add some extra information for 'ksh -R file' to the man page. This patch
  is from Red Hat: https://git.centos.org/rpms/ksh/blob/c8/f/SOURCES/ksh-20080202-manfix.patch

src/lib/libast/comp/realpath.c

@@ -44,7 +44,7 @@ extern int		resolvepath(const char*, char*, size_t);
 extern char*
 realpath(const char* file, char* path)
 {
-	// @lkoutsofios path may be NULL
+	/* @lkoutsofios: path may be NULL */
 	if (!path) {
 	    	if (!(path = malloc (PATH_MAX)))
         		return NULL;

src/lib/libast/man/tm.3

@@ -70,7 +70,7 @@ are used to determine local time zone and savings time information.
 .PP
 .L time_t
 values are the number of seconds since the epoch,
-.BR "Jan 1 00:00:00 GMT 1970" ,
+.BR "Jan 1 00:00:00 UTC 1970" ,
 with leap seconds omitted.
 .PP
 The global variable
@@ -433,7 +433,7 @@ that includes the hours and minutes.
 .B z
 Time zone
 .I SHHMM
-west of GMT offset where
+west of UTC offset where
 .I S
 is
 .B +
@@ -614,7 +614,7 @@ Meridian names: AM, PM.
 .TP
 .B 43-46
 .B UTC
-time zone names: GMT, UTC, UCT, CUT.
+time zone names: UTC, UCT, CUT, GMT.
 .TP
 .B 47-50
 Daylight savings time suffix names: DST.

src/lib/libast/man/tmx.3

@@ -59,7 +59,7 @@ are used to determine local time zone information.
 .PP
 .L time_t
 values are the number of seconds since the epoch,
-.BR "Jan 1 00:00:00 GMT 1970" ,
+.BR "Jan 1 00:00:00 UTC 1970" ,
 with leap seconds omitted.
 .PP
 The global variable
@@ -492,7 +492,7 @@ Meridian names: AM, PM.
 .TP
 .B 43-46
 .B UTC
-time zone names: GMT, UTC, UCT, CUT.
+time zone names: UTC, UCT, CUT, GMT.
 .TP
 .B 47-50
 Daylight savings time suffix names: DST.

src/lib/libast/uwin/random.c

@@ -71,7 +71,7 @@ extern long int	random();
    then initialized to contain information for random number generation with
    that much state information.  Good sizes for the amount of state
    information are 32, 64, 128, and 256 bytes.  The state can be switched by
-   calling the setstate() function with the same array as was initiallized
+   calling the setstate() function with the same array as was initialized
    with initstate().  By default, the package runs with 128 bytes of state
    information and generates far better random numbers than a linear
    congruential generator.  If the amount of state information is less than