Moved all of the mqtt specific files to a separate build directory. The intention is to be able to use it as a git subtree module in other projects

Makefile

@@ -27,7 +27,7 @@ ESPPORT		?= COM3
 TARGET		= app
 
 # which modules (subdirectories) of the project to include in compiling
-MODULES		= driver user
+MODULES		= driver mqtt user
 EXTRA_INCDIR    = include $(SDK_BASE)/../include
 
 # libraries used in this project, mainly provided by the SDK

Makefile.linux

@@ -24,7 +24,7 @@ ESPPORT		?= /dev/ttyUSB0
 TARGET		= app
 
 # which modules (subdirectories) of the project to include in compiling
-MODULES		= driver user
+MODULES		= driver mqtt user
 EXTRA_INCDIR    = include $(SDK_BASE)/../include
 
 # libraries used in this project, mainly provided by the SDK

Makefile.windows

@@ -27,7 +27,7 @@ ESPPORT		?= COM3
 TARGET		= app
 
 # which modules (subdirectories) of the project to include in compiling
-MODULES		= driver user
+MODULES		= driver mqtt user
 EXTRA_INCDIR    = include $(SDK_BASE)/../include
 
 # libraries used in this project, mainly provided by the SDK

mqtt/Makefile

@@ -0,0 +1,44 @@
+
+#############################################################
+# Required variables for each makefile
+# Discard this section from all parent makefiles
+# Expected variables (with automatic defaults):
+#   CSRCS (all "C" files in the dir)
+#   SUBDIRS (all subdirs with a Makefile)
+#   GEN_LIBS - list of libs to be generated ()
+#   GEN_IMAGES - list of images to be generated ()
+#   COMPONENTS_xxx - a list of libs/objs in the form
+#     subdir/lib to be extracted and rolled up into
+#     a generated lib/image xxx.a ()
+#
+ifndef PDIR
+GEN_LIBS = libdriver.a
+endif
+
+
+#############################################################
+# Configuration i.e. compile options etc.
+# Target specific stuff (defines etc.) goes in here!
+# Generally values applying to a tree are captured in the
+#   makefile at its root level - these are then overridden
+#   for a subtree within the makefile rooted therein
+#
+#DEFINES += 
+
+#############################################################
+# Recursion Magic - Don't touch this!!
+#
+# Each subtree potentially has an include directory
+#   corresponding to the common APIs applicable to modules
+#   rooted at that subtree. Accordingly, the INCLUDE PATH
+#   of a module can only contain the include directories up
+#   its parent path, and not its siblings
+#
+# Required for each makefile to inherit from the parent
+#
+
+INCLUDES := $(INCLUDES) -I $(PDIR)include
+INCLUDES += -I ./
+PDIR := ../$(PDIR)
+sinclude $(PDIR)Makefile
+