Fixes issues #2783 #1943 #1509 #2017 and #2298

[fe-cj]

• Fixes #2783, now margins of nodes with relativePosition or absolutePosition are ignored and don't interfere with the regular flow of the layout.
• Fixes #1943 #1509 #2017 and #2298: They are all the same bug, the problem was that when a page break was produced and there was a snapshot stored (columns or tables; detached blocks also generate a snapshot but since we are ignoring their margins now, no need to do anything), it was calculating the new available width of the top parent snapshot without taking into consideration the lateral margins of the node that produced the snapshot.
• It also fixes a small bug introduced by PR #1402 that made the code not to apply the lateral margins of a node after a page break was produced by its margins.

[liborm85]

Excellent work, thanks.

[fe-cj]

It also fixes #2671