-some python2.5 compatibility
-moved platform_py to system.py, turned into singleton
-added shell detection to system.py
-improved on existing shell detection via psutil module, this is also x-platform
-added settings API
-removed some settings from configure/install.sh, now handled at runtime by settings singleton instead
-fixed rez-dot so you can change img format; changed default from jpg to png,
 jpg has issues on old centOS distros;
-added rezconfig file, part of new settings system
-ported Rex to use system.py
-removed some now unused settings from configure.sh
-ported remaining use of settings to new settings code
-removed all references to filesys.py
-removed filesys.py
-added rez-settings tool, which views current settings
-updated resolver code so that packages_path can be passed to the resolver,
this cleans up code in rez-env autowrapper
-fixed bug that meant subshells were broken
-misc python2.5 compatibility

Merge branch 'luma_ext_blds' into rez_install_cli
Conflicts:
	bin/_set-rez-env
	configure.sh
	install.sh
	python/rez/config.py
	python/rez/release.py
	python/rez/util.py