Option to avoid generating files for items with short comments

[kiith-sa]

Currently, if a class has 10 documented data members which only have a 1-line description comment, it has 10 deceiving links to almost empty files that will get the user no new information. For DDox link compatibility we want to keep this, but it would be useful to have an option not to generate these files, and instead put the detailed description (with any info missing from parent file) to the parent file.

Also, an option to not generate files for any members other than functions, templates or aggregates may help as well. There still need to be anchors with easily copiable permalinks, though.