Multi-byte buffer handling.

Multi-byte buffer handling.
(ps-print-version): New version number (4.0) and doc fix.
(ps-color-device, ps-face-bold-p, ps-face-italic-p): Conditional
compilation for GNU Emacs and emacsens.
(ps-generate-postscript-with-faces): Force invisible text to be
visible.
(dos-ps-printer): New var to avoid compilation gripes.

(ps-mule-plot-string): Pay attention to the case
that no more characters can't be printed in the current line.

(ps-mule-find-wrappoint): ENDPOS should not be greater than TO.

Add codes to make ps-print.el work also on Emacs
20.2 and the earlier version.
(ps-mule-encode-7bit, ps-mule-encode-8bit): Modified for 20.2.
(ccl-encode-ethio-unicode, ps-mule-encode-ethiopic): Likewise.
(ps-mule-find-wrappoint): Likewise.
(ps-mule-generate-font): Change `X' to `x' in format
control-string.
(ps-generate): Call ps-mule-begin before calling ps-begin-job.
(ps-mule-cmpchar-prologue): Delete unnecessary `gsave' and
`restore' form procedures `BC' and `EC'.

(ps-print-prologue-1): Handle the case that FontBBox
is an executable procedure.  Make LineThickness, Xshadow, and
Yshadow relative to FontHeight.  Set SpaceWidth in BeginDoc.
(ps-mule-font-info-database, ps-mule-font-info-database-ps,
ps-mule-font-info-database-bdf): New vars.
(ps-mule-encode-7bit, ps-mule-encode-8bit): New funs.
(ccl-encode-ethio-unicode): New CCL program.
(ps-mule-encode-ethiopic): New fun.
(ps-mule-current-charset): New var.
(ps-mule-get-font-spec, ps-mule-font-spec-src,
ps-mule-font-spec-name, ps-mule-font-spec-encoding,
ps-mule-font-spec-bytes, ps-mule-printable-p): New funs.
(ps-mule-external-libraries): New var.
(ps-mule-init-external-library): New fun.
(ps-mule-font-cache): New var.
(ps-mule-generate-font, ps-mule-generate-glyphs): New funs.
(ps-last-font): New var.
(ps-mule-prepare-font): New fun.
(ps-mule-charset-list): New var.
(ps-mule-prologue-generated, ps-mule-prologue): New vars.
(ps-mule-skip-same-charset, ps-mule-find-wrappoint,
ps-mule-plot-string): New funs.
(ps-mule-cmpchar-prologue-generated, ps-mule-cmpchar-prologue):
New vars.
(ps-mule-plot-rule-cmpchar, ps-mule-plot-cmpchar,
ps-mule-prepare-cmpchar-font): New funs.
(ps-mule-bitmap-prologue-generated, ps-mule-bitmap-prologue): New
vars.
(ps-mule-generate-bitmap-prologue, ps-mule-generate-bitmap-font,
ps-mule-generate-bitmap-glyph): New funs.
(ps-mule-initialize, ps-mule-begin): New funs.
(ps-output-string-prim): Insert string as unibyte.
(ps-output-prologue): New fun.
(ps-flush-output): Handle the case of 'prologue.
(ps-begin-file): Call ps-mule-initialize.
(ps-begin-job): Set ps-control-or-escape-regexp differently if
printing multibyte characters.
(ps-begin-page): Set ps-mule-current-charset to 'ascii.
(ps-basic-plot-string): Handle the case of printing ASCII
characters by external libraries (e.g. BDF).
(ps-set-font): Set ps-last-font.
(ps-plot-region): Handle multibyte characters, use
ps-mule-plot-string for them.
(ps-generate): Set the spool buffer unibyte.  Call ps-mule-begin.