[mesh] mesh frame editing part-2 - start, commit, roll back and cancel#43982

Merged

PeterPetrik merged 9 commits intoqgis:masterfrom vcloarec:start_mesh_editing

Jul 1, 2021

+955-169

Commits on Jun 29, 2021

Commits on Jul 1, 2021

simplified
vcloarec
committed