Delete old bindings

bindings/old/README.md

bindings/old/authenticatedChannels.go

bindings/old/backup.go

bindings/old/callback.go

bindings/old/client.go

bindings/old/contact.go

bindings/old/dummy.go

bindings/old/errors.go

bindings/old/errors_test.go

bindings/old/event.go

bindings/old/fileTransfer.go

bindings/old/group.go

bindings/old/jsons.go

bindings/old/jsons_test.go

bindings/old/list.go

bindings/old/message.go

bindings/old/mnemonic.go

bindings/old/ndf.go

bindings/old/ndf_test.go

bindings/old/notifications.go