Add cereal cmake

cmake/FindCereal.cmake

+# CMake module for find_package(CEREAL)
+# Finds include directory and all applicable libraries
+
+# This sets the following variables:
+# CEREAL_FOUND - True if Cereal was found.
+# CEREAL_INCLUDE_DIRS - Directories containing the Cereal include files.
+# CEREAL_DEFINITIONS - Compiler flags for Cereal.
+
+find_path(CEREAL_INCLUDE_DIR cereal
+        HINTS "${CEREAL_ROOT}/include" "$ENV{CEREAL_ROOT}/include" "/usr/include" "$ENV{PROGRAMFILES}/cereal/include" "cereal/include")
+
+set(CEREAL_INCLUDE_DIRS ${CEREAL_INCLUDE_DIR})
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Cereal DEFAULT_MSG CEREAL_INCLUDE_DIR)
+
+mark_as_advanced(CEREAL_INCLUDE_DIR)
+
+if(CEREAL_FOUND)
+    message(STATUS "Cereal found (include: ${CEREAL_INCLUDE_DIRS})")
+endif(CEREAL_FOUND)