[Finishes #82528174]
Create embeddable game from Blockly level with query parameter ?embed=true
(embedded frame responds to changes in screen/iframe width)
Added 'iframe' parameter to content dsl type
include iframe embed in multi puzzle type
show embedded level. More work on resizing iframe based on width.
fix issue with initial resize
Tweaks to admin panel stylesheet
[Finishes #83088252] Create "embed" Blockly (Play Lab) level option that hides the Blockly workspace.
display instructions in embed level mode
Removed 'iframe' method from content DSL (use '.level' extension URLs instead)
remove unused variable
Remove unused variable
Merge pull request #416 from code-dot-org/82528174_playlab_embed_iframe

[Delivers #82528174 #83088252] Playlab Embeddable iFrame