Refactoring: remove _objects_pool, move target_srcs_map out of blade.py
move scons_rules to Target and remove unused Target.get
Fix test warning
make Blade.build_rules_generator not member
Refactoring dependancy analysisi
Refactoring blade.py, distinguish between current_source_dir and root_dir
Refactoring blade.py: move unrelated vars outside and remove unused functions
Refactoring blade.py: improve interface of ctor
Refactoring tests
Merge pull request #65 from chen3feng/develop