Correct layout rect result of element in `StackLayout` (#5)

* Correct layout rect result of element in `StackLayout`

* Update StackLayoutTests.swift

[Fix] Correct layout for items with explicit zero length (#4)

* [Fix] Correct layout for items with explicit zero length

* Add correct initialization for `StackLayoutBuilder`; Removed init with `Size` from `SizeLayout`

Update StackLayoutBuilder.swift (#3)

Add function builders for stack- and z- layouts

[Fix] Visibility of inset factory methods

Correct sizing for `ZLayout.calculateSize(in:)`

Add button layout sizing options to layout with the container or cust…

…om height.

Update `@discardableResult`attribute usage

[Fix] `InsetLayout.calculateSize` respects child size

Create ci.yml