add implot and start using it

external/implot/CMakeLists.txt

@@ -0,0 +1,31 @@
+cmake_minimum_required(VERSION 3.24 FATAL_ERROR)
+
+include(FetchContent)
+
+if (NOT TARGET implot)
+	FetchContent_Declare(implot
+		GIT_REPOSITORY https://github.com/epezent/implot.git
+		GIT_TAG 47522f47054d33178e7defa780042bd2a06b09f9 # 22-01-2025
+		EXCLUDE_FROM_ALL
+		CONFIGURE_COMMAND "" # no cmake
+	)
+
+	FetchContent_GetProperties(implot)
+	if(NOT implot_POPULATED)
+		FetchContent_MakeAvailable(implot)
+
+		add_library(implot STATIC
+			${implot_SOURCE_DIR}/implot.h
+			${implot_SOURCE_DIR}/implot_internal.h
+
+			${implot_SOURCE_DIR}/implot.cpp
+			${implot_SOURCE_DIR}/implot_demo.cpp
+			${implot_SOURCE_DIR}/implot_items.cpp
+		)
+		target_include_directories(implot PUBLIC ${implot_SOURCE_DIR})
+		target_compile_features(implot PUBLIC cxx_std_11)
+		target_link_libraries(implot PUBLIC imgui)
+		#target_compile_definitions(implot PUBLIC IMGUI_USE_WCHAR32)
+	endif()
+endif()
+