[FIX] doc: latex building

* add latex support for exercise admonition
* latex freezes/crashes on {HEAVY WIDE-HEADED RIGHTWARDS ARROW} so
  replace them by more manual arrows
* add some preamble configuration, may not even be necessary
* generate WS setup code only in HTML output. WS doc in latex still
  isn't great as it displays all 4 languages one after the other,
  ideally they should be tagged or something, so only one language at a
  time is generated in non-HTML outputs

doc/_themes/odoodoc/__init__.py

@@ -15,6 +15,9 @@ def setup(app):
     app.add_node(exercise, html=(
         lambda self, node: self.visit_admonition(node, 'exercise'),
         lambda self, node: self.depart_admonition(node)
+    ), latex=(
+        lambda self, node: self.visit_admonition(node),
+        lambda self, node: self.depart_admonition(node)
     ))
 
 from docutils import nodes

doc/api_integration.rst

@@ -24,6 +24,8 @@ Connection and authentication
 
 .. kinda gross because it duplicates existing bits
 
+.. only:: html
+
     .. rst-class:: setupcode hidden
 
         .. code-block:: python

doc/conf.py

@@ -166,6 +166,12 @@ html_sidebars = {
 # base URL from which the finished HTML is served.
 #html_use_opensearch = ''
 
+latex_elements = {
+    'papersize': r'a4paper',
+    'preamble': u'''\\setcounter{tocdepth}{2}
+''',
+}
+
 # default must be set otherwise ifconfig blows up
 todo_include_todos = False
 

doc/howtos/backend.rst

@@ -1241,10 +1241,10 @@ Workflows are also used to track processes that evolve over time.
     In the session form, add a (read-only) field to
     visualize the state, and buttons to change it. The valid transitions are:
 
-    * Draft ➔ Confirmed
-    * Confirmed ➔ Draft
-    * Confirmed ➔ Done
-    * Done ➔ Draft
+    * Draft -> Confirmed
+    * Confirmed -> Draft
+    * Confirmed -> Done
+    * Done -> Draft
 
     .. only:: solutions