As minimum CMake version required to build CMake itself is set to 3.13,
including this module from the source directory isn't needed anymore,
as it was added in CMake 3.8. This also enables changing module code
as done in other modules - not dependent on CMake build system itself.
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.
