RFC: replacing MacroLogFeature.cmake with FeatureSummary.cmake

[Alexander Neundorf]

Ok, there is now a branch FeatureSummaryImprovements on the cmake stage:
http://cmake.org/gitweb?p=stage/cmake.git;a=shortlog;h=refs/heads/FeatureSummaryImprovements

It should have everything discussed here:
* every package can have multiple PURPOSEs
* every package has a dependency TYPE: RUNTIME < OPTIONAL < RECOMMENDED < 
REQUIRED

* optionally, feature_summary() can abort if a REQUIRED package has not been 
found


Usage is like this:

find_package(LibXml2)
# the following one ideally directly inside LibXml2:
set_package_properties(LibXml2 PROPERTIES
                               DESCRIPTION "XML processing library."
                               URL "http://xmlsoft.org/")

# and in the using project
set_package_properties(LibXml2 PROPERTIES
    PURPOSE "Required for exporting spreadsheets to odt format in kspread"
    TYPE RECOMMENDED
    )


# and in some other part of the project:
set_package_properties(LibXml2 PROPERTIES
                PURPOSE "Required for importing html files in kword"
                TYPE OPTIONAL )

# or all in one call:
find_package(DBus)
set_package_properties(DBus PROPERTIES 
                DESCRIPTION "A desktop IPC bus"
                URL "http://dbus.freedesktop.org>"
                TYPE RUNTIME
                PURPOSE "Required to disable the screensaver via kpresenter")


The call to feature_summary() equivalent to what we have now is:
feature_summary(WHAT ALL   FATAL_ON_MISSING_REQUIRED_PACKAGES)


Please give it a try, let me know about issues you find or whether it's just 
nice.
Also, I'm happy about patches which improve the documentation or the output 
format (or anything else).

Alex