Lagom: Import the beginnings of a "port" of Serenity libs for the outside.

The C++ facilities of Serenity are getting pretty comfortable, and I'd like
to take them with me to projects outside the system.

Let's make it a bit easier to do that by bundling AK and LibCore (for now)
into a portable library called "Lagom". :^)

Lagom/.gitignore

@@ -0,0 +1,4 @@
+CMakeCache.txt
+CMakeFiles
+Makefile
+cmake_install.cmake

Lagom/CMakeLists.txt

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+cmake_minimum_required (VERSION 2.6)
+
+set(CMAKE_C_COMPILER clang)
+set(CMAKE_CXX_COMPILER clang)
+set(CMAKE_CXX_FLAGS "-O2 -Wall -Wextra -Wconsumed -Werror -std=c++17")
+
+project (Lagom)
+
+file(GLOB SOURCES "../Libraries/LibCore/*.cpp")
+
+set(SOURCES ${SOURCES}
+    ../AK/StringImpl.cpp
+    ../AK/String.cpp
+    ../AK/JsonArray.cpp
+    ../AK/JsonValue.cpp
+    ../AK/JsonObject.cpp
+    ../AK/JsonParser.cpp
+    ../AK/StringBuilder.cpp
+    ../AK/StringView.cpp
+    ../AK/LogStream.cpp
+)
+
+include_directories (../)
+include_directories (../Libraries/)
+add_library(lagom SHARED ${SOURCES})
+

Lagom/ReadMe.md

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+# Lagom
+
+The Serenity C++ library, for other Operating Systems.
+
+## About
+
+If you want to bring the comfortable Serenity classes with you to another system, look no further. This is basically a "port" of the `AK` and `LibCore` libraries to generic \*nix systems.
+
+*Lagom* is a Swedish word that means "just the right amount." ([Wikipedia](https://en.wikipedia.org/wiki/Lagom))