feat(dia.Graph): add transferCellEmbeds() and transferCellConnectedLinks()

[MartinKanera]

Description

Add graph.transferCellEmbeds() and graph.transferCellConnectedLinks().
Change the dia.Cell.embed method to accept opt.reparent.

Documentation

transferCellEmbeds()

graph.transferCellEmbeds(sourceCell, targetCell [, opt]);

Transfer embedded cells of sourceCell to targetCell.

transferCellConnectedLinks()

graph.transferCellConnectedLinks(sourceCell, targetCell [, opt]);

Transfer all the links connected to sourceCell to targetCell.

embed()

...

The opt.reparent option can be set to true to transfer the embedded cells from their current parent to the new parent.

[kumilingus]

Both methods should run inside a batch:
transfer-links
transfer-hiearchy

[zbynekstara]

Thoughts on the naming of the functions:

• graph.transferCellHierarchy is not ideal because it makes it seem that target cell will not be modified (only passively receiving the children of source element), but I have trouble coming up with a better name. I don't think the word cellHierarchy makes it obvious that target will also be reparented to source's parent. I don't think these two separate actions can be captured by a single word - perhaps the name should be split to describe the two actions separately and more precisely, like graph.transferCellEmbedsAndReparent?
• graph.transferCellLinks is okay, but since we already have cell.getConnectedLinks, graph.transferCellConnectedLinks would be more consistent

[MartinKanera]

Thoughts on the naming of the functions:

• graph.transferCellHierarchy is not ideal because it makes it seem that target cell will not be modified (only passively receiving the children of source element), but I have trouble coming up with a better name. I don't think the word cellHierarchy makes it obvious that target will also be reparented to source's parent. I don't think these two separate actions can be captured by a single word - perhaps the name should be split to describe the two actions separately and more precisely, like graph.transferCellEmbedsAndReparent?
• graph.transferCellLinks is okay, but since we already have cell.getConnectedLinks, graph.transferCellConnectedLinks would be more consistent

transferCellEmbeds (add Cell.embed opt.reparent) and transferCellConnectedLinks