Use align-items:stretch in column-parted

Refine

• align-items: stretch in column-parted.

Add column-parted

Feature

• adding column-parted, which is experimental.

Change layout aliases

Feature

• removed column-center, not used
• adding row-dispersive, column-dispersive
• update demo page

Add row-parted

Feature

• row-parted to render buttons at right.