CHANGES IN WAF 2.1.0
--------------------
* While the Waf file runs on Python 2 and 3, creating it requires version 3
+ Added wafcache
+ waf_unit_test: Added task in returned tuples, custom reports should be adapted
~ Ensure ConfigurationContext.load and Context.load definitions are consistent and remove unused *k parameters
- Remove waflib.Runner.PriorityTasks.appendleft
- Remove waflib.Task.TaskBase
- Remove the upper class of waflib.Task.Task (metaclass syntax)
- Remove Winphone/WinCE detection in msvc.py
- Remove conf.add_as_needed because it does not check for the flag usage

CHANGES IN WAF 2.0.0
--------------------
* Provide a new priority system to improve scalability on complex builds
* Provide TaskGroup objects to improve scalability on complex builds
* Force new files into the build directory by default (use Node objects to bypass)
* Provide built-in support for building over UNC paths
* Simplify the Task class hierarchy; TaskBase is removed
* Display commands as string with "WAF_CMD_FORMAT=string waf build -v"
* Have ant_glob(..., generator=True) return a Python generator
* Accept nested lists and generators in bld(source=...)
* Sort TaskGen methods in alphabetical order by reversing TaskGen.prec order

- Remove 'ut_fun' from waf_unit_test.py
- Remove Node.sig and Node.cache_sig
- Remove the BuildContext.rule decorator
- Remove Task.update_outputs, Task.always_run
- Remove atleast-version, exact-version and max-version from conf.check_cfg
- Remove c_preproc.trimquotes
- Remove field_name, type_name, function_name from conf.check() tests
- Remove extras/mem_reducer.py as a better solution has been merged
- Remove Utils.ex_stack (use traceback.format_exc())