The 'source_files' param to the xcode6 tool was originally separated from the
conventional 'source' param because it was used to control how the source files
would appear in the XCode folder UI. Also, it'd allow to add any file extensions,
and not limited to those extensions supported by the loaded set of waf tools.
This commit renames 'source_files' param to 'group_files'. It also changes the semantic so that 'group_files' now is used like the following:
bld(
source='...', # These are now the files compiled by XCode
'group_files': ..., # Optionally customize the way source files appear i the UI
)
Previously, 'source_files' was used to collect source files for compilation in XCode, and to customize the UI folder structure. In this commit source_files is used only to let the user group files in different UI folders (and add additional resource files besides source files). I want to do the renaming to better reflect the param's meaning.
Additional changes:
* Remove unique_filereference
* Updated examples
