Issue #260: Construction help lines / guides (dismine/valentina)

New issue 260: Construction help lines / guides https://bitbucket.org/valentinateam/valentina/issue/260/construction-help-lines-guides

Felix Ulber:

Using Mueller and Son, theres are cases, where you start construction by e.g. the back mid line, plotting down several measures at different heights. Then start constructing the first piece (back), but use those lines to construct also side and front pieces.

A the moment this means I have to draw abritraty long horizontal lines at these plots. No. I just realized I am talking about separate pattern pieces, so there is actually no possibility at all for me to re-use some parts of the construction of one piece as a base for the construction of a second.

It would probably need something like horizontal guides to help in this case. Or the ability to use the “Point from x and y” tool among different pattern pieces.

So there is a need for kinds of construction helper means which - this may include several different things I think. So this is rather to be the trigger for a dicussion than a clear and obvious issue.

Input and contribution appreciated!