Update to 1.8.0:

NEW IN WAF 1.8.0
----------------
* Python 2.5 is now required
* Removed the Waf cache from the task level, use the netcache system
* Console handling improvements
* Properly-sized progress bar on windows
* Generic configuration tests
* Better unicode handling in scripts and in file names
* Shorter build outputs
* Prevent external static libraries propagation through uselib vars #1320
* LaTeX glossaries #1342 and multibib #1345
* Rst document processing
* Various improvements in the Python detection and processing
* Tons of bugfixes

(wiz)