Lots of man page fixes and some other minor fixes (#284)

Noteworthy changes:
- The man pages have been updated to fix a ton of instances of
  runaway underlining (this was done with `sed -i 's/\\f5/\\f3/g'`
  commands). This commit dramatically increased in size because
  of this change.
- The documentation for spawnveg(3) has been extended with
  information about its usage of posix_spawn(3) and vfork(2).
- The documentation for tmfmt(3) has been updated with the changes
  previously made to the man pages for the printf and date builtins
  (though the latter builtin is disabled by default).
- The shell's tracked alias tree (hash table) is now documented in
  the shell(3) man page.
- Removed the commented out regression test for an ERRNO variable
  as the COMPATIBILITY file states it was removed in ksh93.

src/lib/libast/port/astlicense.c

@@ -953,7 +953,7 @@ astlicense(char* p, int size, char* file, char* options, int cc1, int cc2, int c
 			comment(&notice, &buf, NiL, 0, 0);
 			COMMENT(&notice, &buf, "You should have received a copy of the", 0);
 			COMMENT(&notice, &buf, "GNU General Public License", 0);
-			COMMENT(&notice, &buf, "along with this software (see the file COPYING.)", 0);
+			COMMENT(&notice, &buf, "along with this software (see the file COPYING).", 0);
 			COMMENT(&notice, &buf, "If not, a copy is available at", 0);
 			COMMENT(&notice, &buf, "http://www.gnu.org/copyleft/gpl.html", 0);
 			comment(&notice, &buf, NiL, 0, 0);