Simple cleanups and reorganization

Author: milseman

Package.swift

@@ -56,11 +56,6 @@ let package = Package(
             name: "_RegexParser",
             dependencies: [],
             swiftSettings: privateStdlibSettings),
-        .testTarget(
-            name: "MatchingEngineTests",
-            dependencies: [
-                "_RegexParser", "_StringProcessing"
-            ]),
         .target(
             name: "_CUnicode",
             dependencies: []),