Fix sign inversion bug in Base1DMapper.
OCD: import order.
Split tests.
Tests which demonstrate issues with linearmapper
Merge branch 'revived-fix/set-screen-bounds' into fix/stretch-data-false

Conflicts:
	chaco/tests/linearmapper_test_case.py
Fix base1dmapper and reversed tests.
Get rid of #%^&%@! print statements
Additional tests as Mark suggested.
Add some paranoid tests
Fix lifecycle flags on base 1d mapper
Update CHANGES.txt
Merge branch 'master' into fix/stretch-data-false

# Via Ioannis Tziakos (1) and Jonathan Rocher (1)
* master:
  Update cmap_image_plot.py
  no need for scipy
  update change log
  fix issue #220
  add a test for issue #220

Conflicts:
	CHANGES.txt
Merge pull request #227 from enthought/fix/stretch-data-false

Fix stretch_data=False