Update project to Xcode 9.3

Author: emsquared

Encryption Kit.xcodeproj/project.pbxproj

@@ -474,7 +474,7 @@
 		0867D690FE84028FC02AAC07 /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 0900;
+				LastUpgradeCheck = 0930;
 				TargetAttributes = {
 					8DC2EF4F0486A6940098B216 = {
 						ProvisioningStyle = Manual;

Encryption Kit.xcodeproj/xcshareddata/xcschemes/Standard Release.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "0900"
+   LastUpgradeVersion = "0930"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

Resources/Build Configuration/Build Configuration.xcconfig

@@ -13,11 +13,13 @@ CLANG_WARN_BLOCK_CAPTURE_AUTORELEASING = YES
 CLANG_WARN_BOOL_CONVERSION = YES
 CLANG_WARN_COMMA = YES
 CLANG_WARN_CONSTANT_CONVERSION = YES
+CLANG_WARN_DEPRECATED_OBJC_IMPLEMENTATIONS = YES
 CLANG_WARN_EMPTY_BODY = YES
 CLANG_WARN_ENUM_CONVERSION = YES
 CLANG_WARN_INFINITE_RECURSION = YES
 CLANG_WARN_INT_CONVERSION = YES
 CLANG_WARN_NON_LITERAL_NULL_CONVERSION = YES
+CLANG_WARN_OBJC_IMPLICIT_RETAIN_SELF = YES
 CLANG_WARN_OBJC_LITERAL_CONVERSION = YES
 CLANG_WARN_RANGE_LOOP_ANALYSIS = YES
 CLANG_WARN_STRICT_PROTOTYPES = YES