chore(structs): Add collection interface and array-based implementation for use in core

Fixes #7409
chore(tagcloud): move site tagcloud functionality to the tagcloud plugin

fixes #7140
chore(tagcloud): moved tagcloud theme sandbox output to tagcloud plugin
chore(tagcloud): moved tagcloud related views to tagcloud plugin
feature(webapp): Add support for a basic WebApp Manifest file

Fixes #7493
Merge pull request #7503 from ewinslow/structs-collections

chore(structs): Add collection interface and array-based implementation ...
Merge pull request #7531 from ewinslow/webapp-manifest

feature(webapp): Add support for a basic WebApp Manifest file
chore(services): Add missing property doc for entityTable
Merge pull request #7548 from mrclay/dic_entityTable

chore(services): Add missing property doc for entityTable
fix(ckeditor): ckeditor now prevents image drag/drop/paste in editor

fixes #4970
feature(js): extended the usability of rel="toggle"

It is now possible to toggle multiple elements with an completely custom
selector and you can control the toggle effect (slide or direct
hide/show).

This helps for #7508, reduces the need for #5139 and fixes #3070.
chore(tagcloud): moved tagcloud related language strings to plugin
chore(tagcloud): moved tagcloud related css to tagcloud plugin
Merge pull request #7507 from jdalsem/block-ckeditor-image-drop

fix(plugins): ckeditor now prevents image drag/drop/paste in editor
Merge pull request #7538 from jdalsem/improve-toggle-js

feature(js): extended the usability of rel="toggle"
Merge pull request #7510 from jdalsem/move-tagcloud-out-of-core

Move tagcloud out of core
feature(cache): allows using ints as keys in Cache\Pool

Keying based on GUIDs is a common case, we should not require devs to
explicitly cast when using pool. There’s too much risk for errors to
auto-casting floats/bools though.
Merge pull request #7554 from mrclay/cache_keys

feature(cache): allows using ints as keys in Cache\Pool
chore(metadata): Pull most services in MetadataTable into member variables