Add tests for the too few/too many columns scenarios for value-tuples; happy to discuss alternative expectations

Better matching of value-tuple names when wrong number of columns - should return nulls for unmapped

Under the `List Support` section, the sentence opens with `Dapper allow you`, which should instead be `Dapper allows you`. This PR will correct this mistake, restoring balance to the universe.

After originally spotting this, the most minor of mistakes, I decided to leave it and move on with my life, since it likely effected nobody. Four hours passed and the thought that it existed unchecked had fully manifested itself within my subconscious and I was no longer able to continue with my existence knowing that I had seen this mistake and not exercised my power to correct it.

Thank you, and sorry.

Due to the way VS test works (by injecting an executable entry point), the performance tests needed to be factored out. I also organized all of our existing tests better along the way.
Actual code changes to Dapper itself are very minor, only formatting and documentation fixes (which we need many more of).

The build.ps1 script is upated to work, but note that <frameworkAssemblies> is not working in .nuspec inside the packages in the new .csproj system. I consider this to be a blocker. Issue is here: https://github.com/NuGet/Home/issues/4853

* Added fix for Simple.Data tast

Due to the missing .FirstOrDefault() in Simple.Data test, performance
numbers for Simple.Data were too high (better than hand coded data
reader). Added FirstOrDefault() to actually fetch the data.

Update readme to remove notice about requiring open connections

Added Belgrade SqlClient library in the performance benchmark

In the performance benchmark is added Belgrade Sql client data access
library (https://github.com/JocaPC/CLR-Belgrade-SqlClient). This is a
wrapper around ADO.NET classes that executes queries in async manner
using callbacks. "Belgrade.Sql.Client": "0.6.2" is aded in project.json
file, and new flag "BELGRADE" controls should the test be executed.

Related: #683

TODO: All of these need race love in V2, complete re-vamp.

Add GetRowParser documentation/example

added firebird support

Add SqlMapper.RemoveTypeMap() method

Update README with documentation for [ExplicitKey] attribute

This reverts commit 91725fb3.

added firebird sql adapter to allow record insert and key retrieving

Add test DiscriminatedUnionWithMultiMapping

DiscriminatedUnionWithMultiMapping - test for check correct MultiMapping (splitOn) functionality with discriminated row parser.

Update Readme.md

Note: there's still a 1.0.0 vs 1.1.0 quirk here - digging.