Since #2627 (1.4.4), `\code`, and then again at #3116 (1.5)
`\sphinxcode` which is the new name has become more complicated than the
original `\texttt{#1}`. This was to obtain straight quotes in PDF output,
and to allow long inline literals to break across lines.
This means though that users who want to customize `\sphinxcode`, for
example to not only do `\texttt` but to use some colour, have to copy
about 10 lines of complicated LaTeX macros which should be not modified
in any way. This commit moves all the code out of `\sphinxcode` into a
separate macro `\sphinxupquote`.
The LaTeX writer will output `\sphinxcode{\sphinxupquote{foo}}` in place
of former `\sphinxcode{foo}`. Moving the `\texttt` from innermost to
outermost level is with no consequence.
309f38a91f