- lib updates for core packages

In Sqlite, DateTime is stored as String, and custom serializers ultimately use Convert.ChangeType to do the conversion. The generated code however doesn't set the Invariant culture, and the conversion can fail if the current culture doesn't match the standard DateTime serialization format from Sqlite.

* Use loop variable instead of 0

* Changed unit test, added additional nesting level

framework and tooling lib updates; does *NOT* include the full corpus of 3rd party ADO.NET providers

This is a branch cleaning up old `#if` clauses, `.csproj` bits, Linux build compatibility, and a few other tid-bits (broken out by commit).

In general: we're on 3.0 tooling and all previous cruft has been removed.

…cording to their names.

Hand coded version did not operate under the same circumstances as others.

- Add CommandBehavior.SingleResult and CommandBehavior.SingleRow. All other framworks does this under the hood.
- Run SqlCommand.Prepare() (perhaps it should be benchmarked as "Compiled"?)
- Use GetNullableValue because it's easier to read and slightly faster
- _table.Rows was incrementally added, which made the benchmark run slower the longer it executed. Added _table.Rows.Clear() to prevent the growth.
- Changed select to use * like other benchmarks

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