fixup algs contd 3 (#498)

* do not call authenticatorMakeCredential() with separate |rpId| fixes #466

* credID returned by authnrGetAssn() is optional if allowCreds has exactly 1 member fixes #472

* fixup global object reference per domenic, improves #472

* indent 4.1.4 step 18et al to clarify relation to prior step

* fix line indent

* do not call authenticatorMakeCredential() with separate |rpId| fixes #466

* credID returned by authnrGetAssn() is optional if allowCreds has exactly 1 member fixes #472

* fixup global object reference per domenic, improves #472

* indent 4.1.4 step 18et al to clarify relation to prior step

* fix line indent

* post rebase-on-master, fix dangling MakeCredentialOptions

* fix error in resolving rebase conflicts

* further rebase conflict resolution error fixups

* convert switch steps to colon-denotation

* tag 'while'

* primary changes for improving #472 mostly complete

* further issue #472 cleanups

* del 'cancel the timer' from #creatCredential fixes #535

* polish constructResultantCredentialCallback method description

* incorp comments from mikewest at webappsec-credential-management/pull/100

* rebased onto master

* credID returned by authnrGetAssn() is optional if allowCreds has exactly 1 member fixes #472

* fixup global object reference per domenic, improves #472

* indent 4.1.4 step 18et al to clarify relation to prior step

* fix line indent

* do not call authenticatorMakeCredential() with separate |rpId| fixes #466

* credID returned by authnrGetAssn() is optional if allowCreds has exactly 1 member fixes #472

* post rebase-on-master, fix dangling MakeCredentialOptions

* fix error in resolving rebase conflicts

* convert switch steps to colon-denotation

* tag 'while'

* primary changes for improving #472 mostly complete

* further issue #472 cleanups

* polish constructResultantCredentialCallback method description

* incorp comments from mikewest at webappsec-credential-management/pull/100

* fix indents make BS happy, add some periods

* fix code tags placement

* correct bugs in prior merge conflict resolution, doh

* rm 'the bytes of'

* add missing @@EDITOR-ANCHOR-01A

* auto-number some steps

* re- fix #466 (due to merge-from-master), fix #536

* eliminate callback and just return an algorithm from #createCredential

* continue fix conflicts from merge from master

* fix a couple of issue #466 stragglers in #op-make-cred

* revert to prior AuthenticationExtensions language per jyasskin

* add inline spec issue pointing to issue #657

* minor cleanups, remove issue wrt not explicitly returning |credentialCreationData|

* fix annoying bikeshed warning wrt 'rpEntity'

* correctly fix warning as well as other incorrect markup

Author: equalsJeffH