Spacing - Padding/Margin - mixed unit and auto support

[diggeddy]

Add a MIXed units option that will allow the user to directly enter the value/unit into the field eg. 15%. For padding this will allow for mixing PX/EM/% For margins this could also allow for the auto value to be added for Container ( not grid item container ), Headline and Buttons.

Auto Margins Left / Right on Contained Container Block will allow users to align containers:

For Grid Item Containers auto margins would need to be applied to the gb-grid-column so would require a separate interface. Which could be something as simple as an Horizontal Alignment option on the Grid Container.... will require some testing.

[eastriverstudio]

@diggeddy nice to see this improvement requested. I was only thinking the other day this is needed, so nice to see you've done it already! I like the way you've proposed handling it too and should give us even more control over the way things are or can be aligned. A very common example is I've quite often found myself wanting to align buttons to the bottom of a grid container whilst everything else is flex-start, so being able to add auto margins should help there :)

[echase]

This is brilliant! I propose:

1. Pencil icon UI (More compact than "mix"; represents "custom")
2. Pass user input ~verbatim as CSS attribute -> allows var() and calc() functions as well as novel units

[diggeddy]

Completed in GenerateBlocks 1.8