CMake builtin documentation handling

CMake,CPack,CTest builtin documentation

All CMake tools command line do have some builtin documentation support. The tools (cmake, cpack, ctest) supports a variable subset of:

 ctool --help-command[-list] 
 ctool --help-module[-list]
 ctool --help-variable[-list]
 ctool --help-policy[-list]
 ctool --help-property[-list]
 ctool --help-full
 ctool --help-html

for the detail see:

 cmake --help
 cpack --help
 ctest --help

This builtin documentation comes from 2 different places:

1. static variables in C++ sources
2. text surrounded by markup in CMake script files

Documentation in C++ sources

This is the primary source of builtin documentation.

Documentation markup in CMake script files

This source is available since CMake 2.8.8 and is currently only used by CPack. The idea behind CMake script markup is to be able to document CMake scripts. Documenting a script means being able to put in structured documentation using some comments.

Before 2.8.8, this was available through:

cmake --help-module

which was basically extracting the first block of comments stripping out the comment character ('#').

From 2.8.8 and up we may be able to do more by using a basic markup language which may be used to document - variable - command - section

The markup may then be automatically extracted by ctool (cmake, cpack, ctest) in order to feed their

 --help-variable[s|-list]
 --help-command[s|-list]

command lines options