Makefile.defs: version set to 4.4.0-dev0

- master branch is open for new features to be part of future major
  release, planned to use version number 4.4

Makefile.defs

@@ -95,9 +95,9 @@ INSTALL_FLAVOUR=$(FLAVOUR)
 
 # version number
 VERSION = 4
-PATCHLEVEL = 3
+PATCHLEVEL = 4
 SUBLEVEL =  0
-EXTRAVERSION = -pre2
+EXTRAVERSION = -dev0
 
 # memory manager switcher
 # 0 - f_malloc (fast malloc)