Fix doc build with recent sphinx versions

docs/sphinxext/only_directives.py

@@ -1,87 +1,93 b''
 #
 # A pair of directives for inserting content that will only appear in
 # either html or latex.
 #
 
 from docutils.nodes import Body, Element
 from docutils.writers.html4css1 import HTMLTranslator
-from sphinx.latexwriter import LaTeXTranslator
 from docutils.parsers.rst import directives
 
+# The sphinx API has changed, so we try both the old and new import forms
+try:
+    from sphinx.latexwriter import LaTeXTranslator
+except ImportError:
+    from sphinx.writers.latex import LaTeXTranslator
+
+
 class html_only(Body, Element):
     pass
 
 class latex_only(Body, Element):
     pass
 
 def run(content, node_class, state, content_offset):
     text = '\n'.join(content)
     node = node_class(text)
     state.nested_parse(content, content_offset, node)
     return [node]
 
 try:
     from docutils.parsers.rst import Directive
 except ImportError:
     from docutils.parsers.rst.directives import _directives
 
     def html_only_directive(name, arguments, options, content, lineno,
                             content_offset, block_text, state, state_machine):
         return run(content, html_only, state, content_offset)
 
     def latex_only_directive(name, arguments, options, content, lineno,
                              content_offset, block_text, state, state_machine):
         return run(content, latex_only, state, content_offset)
 
     for func in (html_only_directive, latex_only_directive):
         func.content = 1
         func.options = {}
         func.arguments = None
 
     _directives['htmlonly'] = html_only_directive
     _directives['latexonly'] = latex_only_directive
 else:
     class OnlyDirective(Directive):
         has_content = True
         required_arguments = 0
         optional_arguments = 0
         final_argument_whitespace = True
         option_spec = {}
 
         def run(self):
             self.assert_has_content()
             return run(self.content, self.node_class,
                        self.state, self.content_offset)
 
     class HtmlOnlyDirective(OnlyDirective):
         node_class = html_only
 
     class LatexOnlyDirective(OnlyDirective):
         node_class = latex_only
 
     directives.register_directive('htmlonly', HtmlOnlyDirective)
     directives.register_directive('latexonly', LatexOnlyDirective)
 
 def setup(app):
     app.add_node(html_only)
     app.add_node(latex_only)
 
     # Add visit/depart methods to HTML-Translator:
     def visit_perform(self, node):
         pass
     def depart_perform(self, node):
         pass
     def visit_ignore(self, node):
         node.children = []
     def depart_ignore(self, node):
         node.children = []
 
     HTMLTranslator.visit_html_only = visit_perform
     HTMLTranslator.depart_html_only = depart_perform
     HTMLTranslator.visit_latex_only = visit_ignore
     HTMLTranslator.depart_latex_only = depart_ignore
 
     LaTeXTranslator.visit_html_only = visit_ignore
     LaTeXTranslator.depart_html_only = depart_ignore
     LaTeXTranslator.visit_latex_only = visit_perform
     LaTeXTranslator.depart_latex_only = depart_perform