Implement application layout component [WIP]
Add sidebar-heading placeholder
Implement icon class generator for sidebar navigation
Add some more sidebar options
Add default sidebar footer color
Rename application layout css component
Remove phoenix-specific declarations from application layout
Add default property for reference
Prepend all application-layout variables with the component name
Fix collapsed navbar toggle icon
Remove single-declaration full-height placeholder
Rename internal placeholder
Remove generate- and build- prepends from mixins
Rename :cop:
Add variable for collapsed sidebar width
Rename main application layout component and refactor mixins
Use header for variables related to blocks and heading for typography-related ones
Rename main layout block variables
Move mixin params on one line
Rename icon class generator mixin name and params