fixed a bug: [1,2,3,4,5,6]._s("1:-1") should be [2,3,4,5] but not []
fixed difference between _s and python:

[1,2,3,4,5,6]._s("0:") should return [1,2,3,4,5,6] but not [1]

[1,2,3,4,5,6]._s("-1:1:-1") should return [6,5,4,3,2] but not []
make a new build.
add some notes.
Merge pull request #2 from kilnyy/diff-fix

Some difference between _s and python