Allow moving an insertion marker leftwards
Allow moving an insertion marker leftwards

By recognising an insertion marker as invalid if localConnection has
changed, not just if highlightedConnection has changed.

sclements/scratch-blocks,sclements/scratch-blocks,LLK/scratch-blocks,sclements/scratch-blocks,gengshenghong/scratch-blocks,gengshenghong/scratch-blocks,sclements/scratch-blocks,griffpatch/scratch-blocks,LLK/scratch-blocks,LLK/scratch-blocks,gengshenghong/scratch-blocks,LLK/scratch-blocks,griffpatch/scratch-blocks,griffpatch/scratch-blocks,gengshenghong/scratch-blocks,gengshenghong/scratch-blocks,sclements/scratch-blocks,griffpatch/scratch-blocks,LLK/scratch-blocks,griffpatch/scratch-blocks