[beta] UI updates for 1.5.1 (#4429)

* s/Delete Contract/Forget Contract/ (#4237)

* Adjust the location of the signer snippet (#4155)

* Additional building-block UI components (#4239)

* Currency WIP

* Expand tests

* Pass className

* Add QrCode

* Export new components in ~/ui

* s/this.props.netSymbol/netSymbol/

* Fix import case

* ui/SectionList component (#4292)

* array chunking utility

* add SectionList component

* Add TODOs to indicate possible future work

* Add missing overlay style (as used in dapps at present)

* Add a Playground for the UI Components (#4301)

* Playground // WIP

* Linting

* Add Examples with code

* CSS Linting

* Linting

* Add Connected Currency Symbol

* 2015-2017

* 2015-2017

* 2015-2017

* 2015-2017

* 2015-2017

* 2015-2017

* 2015-2017

* Added `renderSymbol` tests

* PR grumbles

* Add Eth and Btc QRCode examples

* 2015-2017

* Add tests for playground

* Fixing tests

* Split Dapp icon into ui/DappIcon (#4308)

* Add QrCode & Copy to ShapeShift (#4322)

* Extract CopyIcon to ~/ui/Icons

* Add copy & QrCode address

* Default size 4

* Add bitcoin: link

* use protocol links applicable to coin exchanged

* Remove .only

* Display QrCode for accounts, addresses & contracts (#4329)

* Allow Portal to be used as top-level modal (#4338)

* Portal

* Allow Portal to be used in as both top-level and popover

* modal/popover variable naming

* export Portal in ~/ui

* Properly handle optional onKeyDown

* Add simple Playground Example

* Add proper event listener to Portal (#4359)

* Display AccountCard name via IdentityName (#4235)

* Fix signing (#4363)

* Dapp Account Selection & Defaults (#4355)

* Add parity_defaultAccount RPC (with subscription) (#4383)

* Default Account selector in Signer overlay (#4375)

* Typo, fixes #4271 (#4391)

* Fix ParityBar account selection overflows (#4405)

* Available Dapp selection alignment with Permissions (Portal) (#4374)

* registry dapp: make lookup use lower case (#4409)

* Dapps use defaultAccount instead of own selectors (#4386)

* Poll for defaultAccount to update dapp & overlay subscriptions (#4417)

* Poll for defaultAccount (Fixes #4413)

* Fix nextTimeout on catch

* Store timers

* Re-enable default updates on change detection

* Add block & timestamp conditions to Signer (#4411)

* Extension installation overlay (#4423)

* Extension installation overlay

* Pr gumbles

* Spelling

* Update Chrome URL

* Fix for non-included jsonrpc

* Extend Portal component (as per Modal) #4392