Huge refactoring for C++ and low-power mode

The display currently shows the time, with hours and minutes, and is
capable of receiving input with buttons (though does nothing). It
sleeps during intervals where nothing is happening. The display task
runs once per second, and RTC alarm A is used for periodic alarms to
update the system time.

Makefile

@@ -24,14 +24,14 @@
 # Tools
 #
 
-TOOL_PREFIX ?= arm-eabi-
+TOOL_PREFIX ?= arm-none-eabi-
 CC			=  $(TOOL_PREFIX)gcc
 CXX			=  $(TOOL_PREFIX)g++
 CPP			=  $(TOOL_PREFIX)cpp
 AS			=  $(TOOL_PREFIX)as
-LD			=  $(TOOL_PREFIX)gcc
+LD			=  $(TOOL_PREFIX)g++
 OBJCOPY		=  $(TOOL_PREFIX)objcopy
-
+STM32_PROG  =  STM32_Programmer.sh
 #
 # Device Variables
 #
@@ -73,13 +73,15 @@ OUTPUT_ELF  ?= $(OUTPUT_NAME).elf
 
 DEVICE_DEFINE = $(subst XX,xx,$(shell echo $(DEVICE_FAMILY) | tr '[:lower:]' '[:upper:]'))
 
+CPU_FLAGS = -mthumb -mcpu=cortex-m0 -mfloat-abi=soft
+
 # C pedantism
 CFLAGS =  -Wall -Wextra -Wpedantic
 # Debug/optimization
-CFLAGS += -ggdb -g3
+CFLAGS += -ggdb -g3 -Os
 CFLAGS += -fdata-sections -ffunction-sections
 # Architecture
-CFLAGS += -mthumb -mcpu=cortex-m0plus
+CFLAGS += $(CPU_FLAGS)
 CFLAGS += -ffreestanding
 # Defines
 CFLAGS += -D$(DEVICE_DEFINE)
@@ -91,12 +93,14 @@ CFLAGS += -I./lib/fonts/
 CXX_FLAGS = -std=c++14 -fno-exceptions -fno-rtti
 
 # Startup Definitions
+ASFLAGS += $(CPU_FLAGS)
 ASFLAGS += -D__STARTUP_CLEAR_BSS
 ASFLAGS += -D__HEAP_SIZE=0 # No heap- let the linker decide it all
 
-LDFLAGS += -lc -lstdc++ -nostdinc -lnosys -Wl,--gc-sections -Wl,--build-id=None
-LDFLAGS += -Wl,--wrap=malloc -Wl,--wrap=free # Fail to compile if dynamic allocation is sneaking through
-LDFLAGS += -mthumb -mcpu=cortex-m0plus
+LDFLAGS += $(CPU_FLAGS)
+LDFLAGS += -Wl,--gc-sections -Wl,--build-id=none -static
+LDFLAGS += -Wl,--wrap=malloc -Wl,--wrap=free # Fail to link if dynamic allocation is sneaking through
+LDFLAGS += -Wl,-print-memory-usage
 
 #
 # Default Target
@@ -126,7 +130,7 @@ $(OUTPUT_BIN): $(OUTPUT_ELF)
 
 $(OUTPUT_ELF): $(LINKER_SCRIPT) $(OBJS)
 	@echo "LD $@"
-	@$(LD) $(LDFLAGS) -T $(LINKER_SCRIPT) -o $(OUTPUT_ELF) $(OBJS)
+	$(LD) -T $(LINKER_SCRIPT) $(LDFLAGS) -o $(OUTPUT_ELF) $(OBJS)
 
 #
 # Utilities
@@ -137,8 +141,7 @@ STM32FLASH_DEVICE = /dev/ttyUSB0
 .PHONY: flash
 flash: $(OUTPUT_BIN)
 	@echo "FLASH $(OUTPUT_BIN)"
-	@st-flash write $(OUTPUT_BIN) 0x8000000
-
+	$(STM32_PROG) --connect port=SWD reset=Hwrst -w $(OUTPUT_BIN) 0x8000000 -v --go
 
 .PHONY: clean
 clean: