Follow up 0bda714

Ensure that mLegendFilterByMap is set before setting the map when
reading legend xml
[composer] Default to setting a map for new legend items

It's friendlier for users, who may not realise they need to set
a map before they can filter legends.
Catch GEOS exceptions when reshape tool is used on non-closed-linestring

And use qWarning() instead of QgsDebugMsg() to make tracing GEOS errors easier
because a stack trace is printed.
Remove workaround for layergroup bug #6938, now fixed
Fix one memory leak + add note to show() calls as they will delete the dialog
Fix #11456 (canvas not refreshed anymore after adding a new feature)

Resorted to a "minimalist" fix - other solutions would potentially break
even more stuff. The handling of non-modal dialogs for add/edit feature
attributes + handling of isModified() should be addressed at some point.
[composer] Respect reference point when resizing scalebar and legend

Previously, the reference point (and data defined position/size) were
ignored when scalebars or legends resized themselves.

Fix #11321, #11380
SIP update: expose QgsAttributeAction icon, iconPath and name

Fix #11458