Fix issue #63: Add support for runtime evaluation in conditional CSS
remove broken test
add visitor to check if there is no constant deficnition inside a conditional node evaluated at runtime
Fix issue #77 and issue #79
fix issue #81
Merge pull request #84 from jDramaix/jd_fix_81

fix issue #81
Merge pull request #83 from jDramaix/jd_fix_77_79

Fix issue #77 and issue #79
Code review
Merge pull request #80 from jDramaix/jd_runtime_conditionnal

Fix issue #63: Add support for runtime evaluation in conditional CSS