Kig Object Groups

[David Narvaez]

Hi all,

I just started a branch in Kig repository, called objectGroups, with
an implementation to improve canceling constructions and undoing them
when a construction involves several points. At the moment, it
effectively squashes bugs 229558[0] and 297484[1], yet it has one
usability disadvantage: the label for unding an action refers to many
objects (e.g., when drawing a circle through three points you are
prompted to undo the creation of four objects) so I plan to address
that situation too before this is merged into master.

Notice that this changes KigPart's API, so these changes would only be
available from 4.9 on. Please review!

David E. Narváez

[0] https://bugs.kde.org/show_bug.cgi?id=229558
[1] https://bugs.kde.org/show_bug.cgi?id=297484