Fixes #15 - Adds new Invoice APIs. Minor fixes.

Update `Flurl.Http` dependency to 3.0.1.

Minimum .NET Framework requirement changed from 4.5 to 4.6.1.
Dropped support for `netstandard1.3`; `netstandard2.0` still supported.

Fixes #12. Fixes error converting null to type 'System.Int64' in char…

…ge payments block height.

release notes. prep release.

history.

Added `CommerceApi.EnableFiddlerDebugProxy()` method to help debug HT…

…TP calls. The method appears for applications using **.NET Standard 2.0** or **Full .NET Framework**. The `EnableFiddlerDebugProxy` will not appear for **.NET Standard 1.3** consumers.

NuGet dependency `Flurl.Http` updated.

NuGet dependency `Newtonsoft.Json` updated.

Make endpoints get properties to avoid segment accumulation and HTTP …

…404s.

Added missing CreateCharge.RedirectUrl.

update history, prep v1.0.1 release.

add paket.exe