Consolidate Linux/Windows Makefiles into one, see http://www.proxmark.org/forum/topic/312/consolidating-makefile/

+ Needs GNU make for Windows, a new release of the Windows development environment will follow
 + Is based on the Windows Makefile, so will build everything in Thumb mode, doesn't have flash commands (yet)

common/Makefile.common

@@ -0,0 +1,43 @@
+# This new makefile replaces the previous Makefile/Makefile.linux
+# with as much common code for both environments as possible.
+# Following is a short OS detection to set up variables, all the
+# remaining Makefile should be portable and only depend on these
+# variables
+
+# Windows' echo echos its input verbatim, on Posix there is some
+#  amount of shell command line parsing going on. echo "" on 
+#  Windows yields literal "", on Linux yields an empty line
+ifeq ($(shell echo ""),)
+# This is properly a proper system, so we can use uname
+UNAME := $(shell uname)
+ifeq ($(UNAME), Linux)
+# Linux. (Todo: Add MacOS X if appropriate)
+DELETE=rm -rf
+PATHSEP=/
+DETECTED_OS=Linux
+# You may/should set this in your environment
+ARMLIB ?= /usr/local/lib/gcc/arm-elf/4.3.3/interwork
+endif
+else
+# Assume that we are running on Windows.
+DELETE=del /q
+PATHSEP=\\#
+ARMLIB ?= ../../devkitARM/lib/gcc/arm-elf/4.1.0/interwork
+DETECTED_OS=Windows
+endif
+
+CC	= arm-elf-gcc
+AS	= arm-elf-as
+LD	= arm-elf-ld
+OBJCOPY = arm-elf-objcopy
+
+OBJDIR	= obj
+
+INCLUDE = -I../include
+
+# Also search prerequisites in the common directory (for usb.c)
+VPATH = . ../common/
+
+INCLUDES = ../include/proxmark3.h ../include/at91sam7s128.h ../include/config_gpio.h ../include/usb_cmd.h $(APP_INCLUDES)
+
+CFLAGS =  -c $(INCLUDE) -Wall $(APP_CFLAGS)