Streamline obsolete color set-up in LaTeX style file

The file ``pdfcolor.tex`` included in tex distributions is for Plain
pdfTeX, not for LaTeX use. Loading it complicates task of supporting
multiple TeX engines. If needed all corresponding colour names are
better available from passing to ``color`` or ``xcolor`` the
``dvipsnames`` option. It is better to leave responsability of using
this option to Sphinx user, if needed. The macros for setting the color
defined by ``pdfcolor.tex`` were never documented to Sphinx user, and
they can not be used from reST apart from ``.. raw:: latex`` directive,
they are for Plain TeX without use of ``color`` package. Thus, this
commit drops loading this file and the complicated conditionals around
it (``\ifsphinxpdfoutput``), which are also used in the class files
``sphinxmanual.cls``, ``sphinxhowto.cls``.

Also, this fixes issue #2693.

sphinx/texinputs/sphinx.sty

@@ -402,33 +402,15 @@
 
 %% COLOR (general)
 %
-% FIXME: the reasons might be obsolete (better color drivers now?)
-% use pdfoutput for pTeX and dvipdfmx
-% when pTeX (\kanjiskip is defined), set pdfoutput to evade \include{pdfcolor}
-\ifx\kanjiskip\undefined\else
-  \newcount\pdfoutput\pdfoutput=0
-\fi
-
-% for PDF output, use colors and maximal compression
-\newif\ifsphinxpdfoutput % used in \maketitle
-\ifx\pdfoutput\undefined\else
- \ifnum\pdfoutput=\z@
-  \let\py@NormalColor\relax
-  \let\py@TitleColor\relax
- \else
-  \sphinxpdfoutputtrue
-  \input{pdfcolor}
-  \def\py@NormalColor{\color[rgb]{0.0,0.0,0.0}}
+% FIXME: \normalcolor should probably be used in place of \py@NormalColor
+% elsewhere, and \py@NormalColor shoudl never be defined. \normalcolor
+% switches to the colour from last \color call in preamble.
+\def\py@NormalColor{\color{black}}
+% FIXME: it is probably better to use \color{TitleColor}, as TitleColor
+% can be customized from 'sphinxsetup', and drop usage of \py@TitleColor
 \def\py@TitleColor{\color{TitleColor}}
-  \pdfcompresslevel=9
- \fi
-\fi
-
-% XeLaTeX can do colors, too
-\ifx\XeTeXrevision\undefined\else
-  \def\py@NormalColor{\color[rgb]{0.0,0.0,0.0}}
-  \def\py@TitleColor{\color{TitleColor}}
-\fi
+% FIXME: this line should be dropped, as "9" is default anyhow.
+\ifdefined\pdfcompresslevel\pdfcompresslevel = 9 \fi
 
 
 %% PAGE STYLING

sphinx/texinputs/sphinxhowto.cls

@@ -31,7 +31,8 @@
 %
 \renewcommand{\maketitle}{%
   \noindent\rule{\textwidth}{1pt}\newline\null\par
-  \ifsphinxpdfoutput
+  % FIXME: use \hypersetup{pdfauthor={\@author}, pdftitle={\@title}}
+  \ifdefined\pdfinfo
     \begingroup
     % These \defs are required to deal with multi-line authors; it
     % changes \\ to ', ' (comma-space), making it pass muster for

sphinx/texinputs/sphinxmanual.cls

@@ -41,7 +41,8 @@
     \let\footnotesize\small
     \let\footnoterule\relax
     \noindent\rule{\textwidth}{1pt}\newline\null\par
-    \ifsphinxpdfoutput
+    % FIXME: use \hypersetup{pdfauthor={\@author}, pdftitle={\@title}}
+    \ifdefined\pdfinfo
       \begingroup
       % These \defs are required to deal with multi-line authors; it
       % changes \\ to ', ' (comma-space), making it pass muster for