help: merge saveproject.page with projectsettings.page
    - move content from saveproject.page to projectsettings.page
    - rename projectsettings.page to workwithprojects.page
    - remove saveproject.page from git
    - remove saveproject.page from Makefile.am
    - update links that pointed to saveproject.page
help: minor improvements in workwithprojects.page
help: minor improvements in layers.page
help: merge makeselections.page with grouping.page
        - move content from makeselections.page to grouping.page
        - rename grouping.page to selectiongrouping.page
        - remove makeselections.page from git
        - remove makeselections.page from Makefile.am
        - update links pointing to makeselections.page
help: minor improvements in selectiongrouping.page