Added more warning flags for GCC (as suggested in issue #28)

src/CMakeLists.txt

@@ -3,4 +3,32 @@ file(GLOB_RECURSE SRC_FILES *.cpp)
 
 include_directories(../include)
 
+if(CMAKE_COMPILER_IS_GNUCXX)
+	add_definitions(
+		-Wall
+		-Wcast-align
+		-Wcast-qual
+		-Wctor-dtor-privacy
+		-Wdisabled-optimization
+		-Wextra
+		-Wformat=2
+		-Winit-self
+		-Wlogical-op
+		-Wmissing-include-dirs
+		-Wno-parentheses
+		-Wno-unused
+		-Wno-variadic-macros
+		-Wnoexcept
+		-Wold-style-cast
+		-Woverloaded-virtual
+		-Wpedantic
+		-Wredundant-decls
+		-Wshadow
+		-Wsign-promo
+		-Wstrict-null-sentinel
+		-Wstrict-overflow=5
+		-Wundef
+	)
+endif()
+
 add_library(ArduinoJson ${SRC_FILES} ${INC_FILES})