* Use OEmbedProviderBase
* Use QueryHelpers.AddQueryString in .NET Core
* Nullable value
* Cleanup usings
* Ensure invariant string
* No need to URL encode when using QueryHelpers.AddQueryString()
* Include WebUtilities
* Cleanup usings
* Revert "Include WebUtilities"
This reverts commit 3cffb740cee8f11bd83cd6e753fba1a04575e5d2.
* Revert "No need to URL encode when using QueryHelpers.AddQueryString()"
This reverts commit 70ca5306ac9343c8825dba48ebd75180b5fd0ecf.
* Revert "Ensure invariant string"
This reverts commit 318ab23f6f2c4605308d767a4e65e7ceb286cebe.
* Revert "Nullable value"
This reverts commit c39911de06812620a08800a1cb72e1197d9972cc.
* Revert to StringBuilder
* Cleanup usings
* Add more descriptions of providers
dcb54c1f6e