CMakePackageConfigHelpers: restructure documentation and document commands
CMakePackageConfigHelpers: Add INSTALL_PREFIX option

This option instructs configure_package_config_file to consider paths
that are not absolute as relative to the INSTALL_PREFIX directory
instead of relative to the CMAKE_INSTALL_PREFIX directory.

If this argument is not passed, the default behaviour is to use
the CMAKE_INSTALL_PREFIX variable.

The new signature is therefore:

  configure_package_config_file(<input> <output> INSTALL_DESTINATION <path>
                                                 [PATH_VARS <var1> <var2> ... <varN>]
                                                 [NO_SET_AND_CHECK_MACRO]
                                                 [NO_CHECK_REQUIRED_COMPONENTS_MACRO]
                                                 [INSTALL_PREFIX <path>])
CMakePackageConfigHelpers: Add unit tests for INSTALL_PREFIX option
Merge topic 'CMakePackageConfigHelpers-INSTALL_PREFIX' into next

e3007c92 CMakePackageConfigHelpers: Add unit tests for INSTALL_PREFIX option
d057bf85 CMakePackageConfigHelpers: Add INSTALL_PREFIX option
f3dd116c CMakePackageConfigHelpers: restructure documentation and document commands
CPackIFW: Refactor and revise this generator

Split the monolithic cmCPackIFWGenerator source into three parts:
cmCPackIFWGenerator, cmCPackIFWInstaller, and cmCPackIFWPackage
to isolate the implementations somewhat.

Add a COMMON option to the cpack_ifw_configure_component command to make
the data component common to its parent group.

Change the default packaging method to ONE_PACKAGE_PER_COMPONENT.
This is not incompatible because the CPack IFW generator has not
yet been in a release.
Merge topic 'cpack-ifw-generator' into next

ebe8d51b CPackIFW: Refactor and revise this generator