Help: More syntax highlighting for literal blocks

Covers almost all blocks containing actual code, except:

* Parsed-literal blocks can't be highlighted, including many command
  summaries and substitution-heavy docs like find_... commands.
  This is a Sphinx limitation.

* Code with errors, like CMP0049, DEPLOYMENT_ADDITIONAL_FILES,
  DEPLOYMENT_REMOTE_DIRECTORY, @PACKAGE_INIT@ substitution in the
  tutorial, bracket arguments/comments in cmake-language.7 and
  cmake-developer.7.

* FindQt4 module, which needs reformatting.

Modules/CMakeAddFortranSubdirectory.cmake

@@ -18,7 +18,7 @@ built into a dll, so :variable:`BUILD_SHARED_LIBS` is turned on in
 the project.  In addition the :variable:`CMAKE_GNUtoMS` option is set
 to on, so that Microsoft ``.lib`` files are created.  Usage is as follows:
 
-::
+.. code-block:: cmake
 
   cmake_add_fortran_subdirectory(
    <subdir>                # name of subdirectory