Added eightfold. (#735)

* Added eightfold.

* Add C++17 flags for eightfold.

* Add comment to explain C++17 flags.

* Undo "Add comment to explain C++17 flags."

* Update license.md to add artwork infomation about eightfold.

* eightfold -> eightfold/*  in LICENSES.md

plugins/Makefile

@@ -707,6 +707,17 @@ PLUGIN_FILES += $(wildcard DrumKit/deps/SynthDevKit/src/*.cpp)
 # modules/types which are present in other plugins
 DRUMKIT_CUSTOM = ADSR Envelope LowFrequencyOscillator
 
+# --------------------------------------------------------------
+# eightfold
+
+PLUGIN_FILES += $(filter-out eightfold/src/plugin.cpp,$(wildcard eightfold/src/*.cpp))
+# modules/types which are present in other plugins
+EIGHTFOLD_CUSTOM = Comparator comparator
+
+
+EIGHTFOLD_FLAGS = $(filter-out -std=gnu++11,$(BUILD_CXX_FLAGS))
+EIGHTFOLD_FLAGS += -std=gnu++17
+
 # --------------------------------------------------------------
 # EnigmaCurry
 
@@ -2347,6 +2358,13 @@ $(BUILD_DIR)/DrumKit/%.cpp.o: DrumKit/%.cpp
 		-Dinit=init__DrumKit \
 		-Wno-sign-compare
 
+$(BUILD_DIR)/eightfold/src/%.cpp.o: eightfold/src/%.cpp
+	-@mkdir -p "$(shell dirname $(BUILD_DIR)/$<)"
+	@echo "Compiling $<"
+	$(SILENT)$(CXX) $< $(EIGHTFOLD_FLAGS) -c -o $@ \
+		$(foreach m,$(EIGHTFOLD_CUSTOM),$(call custom_module_names,$(m),eightfold)) \
+		-DpluginInstance=pluginInstance__eightfold
+
 $(BUILD_DIR)/EnigmaCurry/src/%.cpp.o: EnigmaCurry/src/%.cpp
 	-@mkdir -p "$(shell dirname $(BUILD_DIR)/$<)"
 	@echo "Compiling $<"