refactor: clean up Makefiles

Makefile

@@ -1,18 +1,10 @@
 # https://spin.atomicobject.com/2016/08/26/makefile-c-projects/ was a great
 # base for this Makefile
 
-VERSION := 0.1.0
+-include config.mk
 
-BIN_FILENAME ?= lander
-
-BUILD_DIR ?= build
-SRC_DIR ?= src
-TEST_DIR ?= test
-THIRDPARTY_DIR ?= thirdparty
-
-INC_DIRS ?= include $(THIRDPARTY_DIR)/include trie/include
-LIBS ?= trie m
-LIB_DIRS ?= ./trie/build
+export CFLAGS
+export LDFLAGS
 
 BIN := $(BUILD_DIR)/$(BIN_FILENAME)
 
@@ -31,23 +23,11 @@ BINS_TEST := $(OBJS_TEST:%.c.o=%)
 TARGETS_TEST := $(BINS_TEST:%=test-%)
 TARGETS_MEM_TEST := $(BINS_TEST:%=test-mem-%)
 
-INC_FLAGS := $(addprefix -I,$(INC_DIRS))
-
-# -MMD: generate a .d file for every source file. This file can be imported by
-#  make and makes make aware that a header file has been changed, ensuring an
-#  object file is also recompiled if only a header is changed.
-# -MP: generate a dummy target for every header file (according to the  docs it
-#  prevents some errors when removing header files)
-CFLAGS ?= -MMD -MP -g
-_CFLAGS := $(INC_FLAGS) $(CFLAGS) -Wall -Wextra -DLANDER_VERSION=\"$(VERSION)\"
-
+_CFLAGS := $(addprefix -I,$(INC_DIRS)) $(CFLAGS) -Wall -Wextra -DLANDER_VERSION=\"$(VERSION)\"
 _LDFLAGS := $(addprefix -L,$(LIB_DIRS)) $(addprefix -l,$(LIBS)) $(LDFLAGS)
 
-export CFLAGS
-export LDFLAGS
-
 .PHONY: all
-all: bin
+all: $(BIN)
 
 
 # =====COMPILATION=====
@@ -60,8 +40,7 @@ libtrie:
 	$(MAKE) -C trie
 
 .PHONY: bin
-bin: $(BIN)
-$(BIN): $(OBJS) libtrie
+$(BIN): libtrie $(OBJS)
 	$(CC) -o $@ $(OBJS) $(_LDFLAGS)
 
 $(BUILD_DIR)/$(SRC_DIR)/%.c.o: $(SRC_DIR)/%.c
@@ -111,6 +90,7 @@ $(BUILD_DIR)/$(TEST_DIR)/%.c.o: $(TEST_DIR)/%.c
 		-I$(dir $(@:$(BUILD_DIR)/$(TEST_DIR)/%=$(SRC_DIR)/%)) \
 		-c $< -o $@
 
+
 # =====MAINTENANCE=====
 .PHONY: lint
 lint: