Hi!
This PR tries to fix Dapper.Performance.Tests, actually you can't get [MemoryDiagnoser](https://benchmarkdotnet.org/api/BenchmarkDotNet.Diagnosers.MemoryDiagnoser.html)  stats because 
```IDiagnoser.GetColumnProvider()``` method was gone on BenchmarkDotnet 0.11.2. I choose ```DefaultColumnProviders.Metrics``` because of [this](https://github.com/dotnet/BenchmarkDotNet/issues/1184#issuecomment-507377695), i think it's the most simple way to add stats now.

**Before**
![image](https://user-images.githubusercontent.com/34173061/65264060-1a5f7780-db0e-11e9-9c8c-bb4c69a808df.png)

**After**
![image](https://user-images.githubusercontent.com/34173061/65264158-4f6bca00-db0e-11e9-9313-597b09070ae6.png)

On the other hand i choose removing ```[Ordered]``` as temporal solution of https://github.com/dotnet/BenchmarkDotNet/issues/1238, and yeah, the results are still ordered because of https://github.com/StackExchange/Dapper/blob/9282ef2872e1c82c68c86f31e93e8f1ceaacd409/Dapper.Tests.Performance/Config.cs#L42

**Before**
![image](https://user-images.githubusercontent.com/34173061/65264660-6232ce80-db0f-11e9-9046-9c2d8fc5e2d8.png)

**After**
 (No errors)

Thanks for all!!

Fix issue #418 for DeleteAsync (with tests)

* Handle char correctly

* Add PostgreSQL char test

* Test for string before testing for char

v2 work; primarily prep for split SqlClient

Expose the underlying connection from Rainbow Database so it's easier to use Dapper alongside other DB frameworks (#1257)

* Pass LocalBuilders instead of indexes since ILGenerator already optimizes the opcode used

* Eradicate magic local indexes to make refactoring safer

* String and byte[] tuple elements cause InvalidProgramException

* Stop setting current index local which is nonexistent in ValueTuple deserializer

* prep work for adding Microsoft.Data.SqlClient support/tests; SqlClient dependency is not yet removed

* Failing tests for tuples larger than 7

* Special-case IL generation for ValueTuple

* Make value-processing logic available to ValueTuple generation

* fix #1228 - rev sqlclient to 4.6.0
* use transitive deps for SqlClient

When reading Geometry and Geography values from the database, we need to specify the SRID explicitly to retain it in the DbGeometry / DbGeography type. (#1038)

merging, thanks, and sorry for delay