Function builders, CGFloat, api clean, UIStackViews

[s4cha]

• Adds support for CGFloat for all apis
• sv() is renamed to subviews() for clarity
• subviews() has now its function builder counterpart: subviews{} (no more commas!)
• layout() has now its function builder counterpart: layout {}
• fillVertically(m:) is renamed to fillVertically(padding:)
• fillHorizontally(m:) is renamed to fillHorizontally(padding:)
• fillContainer(x) is renamed to fillContainer(padding: x)
• centerHorizontally(x) is renamed to centerHorizontally(offset: x)
• Double dash -- operator is renamed in hyphen bullet for better compile times. (auto replace)
• Adds UIStackView arrangedSubviews {} function builder