* 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.

Readme: Better explanation for multi mapping

GridReader.IsConsumed wouldn't be true

Non-greedy match for comments regex

Fixes #436, #280
My editor has also normalized a few line endings to LF like 99% of the
file was.

Update readme.md

Missed second bracket in ID example

Make CommandBehavior optimizations more configurable