[Groff] color support in grotty

[Werner LEMBERG]

Finally, here it is!


I've finished color support in grotty and committed it to the CVS.
SGR escape sequences will be the new default.  At the same time, I've
added two new options to nroff.


    Enjoy!

      Werner

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>From the NEWS file:

Grotty
------

o Color support has been added, using the SGR (ISO 6429, sometimes
  called ANSI color) escape sequences.

o SGR escape sequences are now used by default for underlining and
  bold printing also, no longer using the backspace character trick.
  To revert to the old behaviour, use the `-c' switch.

  Note that you have to use the `-R' option of `less' to make SGR
  escapes display correctly.  On the other hand, terminal programs and
  consoles like `xterm' which support SGR sequences natively can
  directly display the output of grotty.  Consequently, the options
  `-b', `-B', `-u', and `-U' work only in combination with `-c' and
  are ignored silently otherwise.

  For the `man' program, it may be necessary to add the `-R' option of
  `less' to the $PAGER environment variable; alternatively, you can
  use `man's `-P' option (or adapt its configuration file
  accordingly).  See man(1) for more details.

o If the new option `-i' is used (only in SGR mode), grotty sends
  escape sequences to set the italic font attribute instead of the
  underline attribute for italic fonts.  Note that many terminals
  don't have support for this (including xterm).

Nroff
-----

o Two new command line options `-c' and `-C'; the former passes `-c'
  to grotty (switching to the old output scheme); the latter passes
  `-C' to groff (enabling compatibility mode).