Updates to the share panel on published apps.
QR code styling update
Removed install spinner from the share page for now.
Hiding install button if an app is already installed
Linting fixes
Fixes
Some double button updates.
More double-button updates
We now make sure custom listeners are added only once with a flag on the element.
fixes boolean behaviour
Added sounds to double button.
Pomax's lint fixes.
Merge pull request #1971 from flukeout/doublebutt

Double button updates
Merge pull request #1970 from Pomax/booleanfix

fixes boolean behaviour
If a brick has both a default listener & broadcast, the designer won't assign the same channel to them.
Merge pull request #1942 from flukeout/sharepane

Share & Remix panel updates.
Audio updates
Merge pull request #1968 from flukeout/eventfix

Ceci-pressdown/up event only being added once to an element bug.
Sound playin' code now makes sure the volume is a number, falls between 0 and 1 (inclusive) and sets it to 1 otherwise.
Merge pull request #1975 from flukeout/defaultchannels

Default channel assignment update