NEW IN WAF 1.9
--------------

* General enhancements:
  - Add the tool 'nobuild.py'
  - Remove qt4 and kde4 from the default modules
  - Have Clang detected first on many platforms, in particular on FreeBSD #1528
  - Remove Node.cache_sig and Node.sig so that dependencies are on file contents #1580
  - Change cflags in the beginning / cppflags at the end #1505
  - Merge ${FOO}${BAR} flags in commands executed without a shell (no space added)
  - Interpret empty command-line defines as integer values #1704
  - Waf tools are not cached on "waf configure" by default anymore; pass conf.load(.., cache=True)

* Performance highlights:
  - Reduce the key size in bld.task_sigs by adding bld.node_sigs and bld.imp_sigs
  - Remove __hash__ and __eq__ from Node and Task #1629
  - Make lazy visual studio detection the default
  - Remove the uses of run_once that creates unfree-able memory
  - Enable a consistent progress bar output #1641
  - Reduce the memory footprint of Task objects, up to 50% memory reduction on large builds
  - Enabled pre-forked builds by default to achieve faster builds, up to 2x speedup on short-lived processes

* API changes:
  - Remove the duplicate split functions from Utils
  - Remove the command called "update"
  - Add Task.get_cwd()
  - Remove Utils.nogc
  - Modify Utils.run_once so that it accepts a list of *args
  - Improve the task consumer in Runner.py
  - Use relative paths in apply_incpaths by default (and absolute ones when paths cross drives)