Refactored for readability
CascadePluginBase got new attr: list glossary_variables can be overloaded to store arbitrary data in glossary from request to request
Using @property on instance instead of polluting the context
Fixed: old values from glossary_variables were not overriden
Container width can now set from breakpoint until breakpoint
Added method get_parent()
Fixed: glossary is updated with key rather than "key"
use strict
Refactored ContainerPlugin to always recalculate its widths