Now that Go 1.13 is the minimum version, we can use the reflect.Value.IsZero
method instead of our own internal/value.IsZero function.
Interestingly, our IsZero function pre-dates the IsZero method,
but fortunately has the exact same semantics, since both are targetting
semantics defined by the Go language specification.

This allows the GoDoc to take advantage of new markup syntax
introduced in Go 1.19. This does not require that our minimum
supported version be bumped to Go 1.19 since the pkgsite renders
our godoc regardless of supported Go version.

Co-authored-by: Damien Neil <[email protected]>

The value.TypeString function is what the rest of the package uses
and is slightly cleaner than using reflect.Type.String.

Updates #305

Co-authored-by: Damien Neil <[email protected]>

* Run tests on Go 1.19

* Format comment

Finish the rest of the work for #304

Co-authored-by: Damien Neil <[email protected]>

If the string has many characters that require escape sequences to print,
then we need to take that into consideration and avoid byte-by-byte diffing.

Co-authored-by: Damien Neil <[email protected]>