Merge Serilog.Extras.AppSettings into the core, in line with serilog#402

Moved in largely as-is, with some work remaining.

Serilog.sln

@@ -24,12 +24,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Serilog.FullNetFx", "src\Se
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Serilog.PerformanceTests", "test\Serilog.PerformanceTests\Serilog.PerformanceTests.csproj", "{6A6504BF-CD5B-4C9E-88EB-5BD71CE3106A}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Serilog.Extras.AppSettings", "src\Serilog.Extras.AppSettings\Serilog.Extras.AppSettings.csproj", "{21CAF132-BBAB-41FD-A018-EB9AE54822ED}"
-EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Serilog.SmokeTest", "test\Serilog.SmokeTest\Serilog.SmokeTest.csproj", "{58563C46-B781-4799-ABD5-9745F94478FD}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Serilog.Extras.AppSettings.Tests", "test\Serilog.Extras.AppSettings.Tests\Serilog.Extras.AppSettings.Tests.csproj", "{67398D2A-0829-4373-ABC5-2161FEB28A05}"
-EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Serilog.MsTests", "test\Serilog.MsTests\Serilog.MsTests.csproj", "{7FC9FC46-5014-4461-A448-815E6CCE21E5}"
 EndProject
 Global
@@ -54,18 +50,10 @@ Global
 		{6A6504BF-CD5B-4C9E-88EB-5BD71CE3106A}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{6A6504BF-CD5B-4C9E-88EB-5BD71CE3106A}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{6A6504BF-CD5B-4C9E-88EB-5BD71CE3106A}.Release|Any CPU.Build.0 = Release|Any CPU
-		{21CAF132-BBAB-41FD-A018-EB9AE54822ED}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{21CAF132-BBAB-41FD-A018-EB9AE54822ED}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{21CAF132-BBAB-41FD-A018-EB9AE54822ED}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{21CAF132-BBAB-41FD-A018-EB9AE54822ED}.Release|Any CPU.Build.0 = Release|Any CPU
 		{58563C46-B781-4799-ABD5-9745F94478FD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{58563C46-B781-4799-ABD5-9745F94478FD}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{58563C46-B781-4799-ABD5-9745F94478FD}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{58563C46-B781-4799-ABD5-9745F94478FD}.Release|Any CPU.Build.0 = Release|Any CPU
-		{67398D2A-0829-4373-ABC5-2161FEB28A05}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{67398D2A-0829-4373-ABC5-2161FEB28A05}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{67398D2A-0829-4373-ABC5-2161FEB28A05}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{67398D2A-0829-4373-ABC5-2161FEB28A05}.Release|Any CPU.Build.0 = Release|Any CPU
 		{7FC9FC46-5014-4461-A448-815E6CCE21E5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{7FC9FC46-5014-4461-A448-815E6CCE21E5}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7FC9FC46-5014-4461-A448-815E6CCE21E5}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -79,9 +67,7 @@ Global
 		{D5648551-D19D-41E3-9FC1-E74B111EEF41} = {0D135C0C-A60B-454A-A2F4-CD74A30E04B0}
 		{7A9E1095-167D-402A-B43D-B36B97FF183D} = {037440DE-440B-4129-9F7A-09B42D00397E}
 		{6A6504BF-CD5B-4C9E-88EB-5BD71CE3106A} = {0D135C0C-A60B-454A-A2F4-CD74A30E04B0}
-		{21CAF132-BBAB-41FD-A018-EB9AE54822ED} = {037440DE-440B-4129-9F7A-09B42D00397E}
 		{58563C46-B781-4799-ABD5-9745F94478FD} = {0D135C0C-A60B-454A-A2F4-CD74A30E04B0}
-		{67398D2A-0829-4373-ABC5-2161FEB28A05} = {0D135C0C-A60B-454A-A2F4-CD74A30E04B0}
 		{7FC9FC46-5014-4461-A448-815E6CCE21E5} = {0D135C0C-A60B-454A-A2F4-CD74A30E04B0}
 	EndGlobalSection
 EndGlobal