Add auto lookup for Python directory.
Fix.
Fix.
Fix.
Fix.
Fix.
Fix sign part.
Fix libswift compile.
Change libswift to test version.
Change swift back to normal.
Revert "Fix libswift compile."

This reverts commit 2e659af1f014645943ae371de3cc155e52e90a6f.
small changes.
Change swift reference.
update swift ref again.
Update swift ref again.
Fix swift ref.
Update swift ref.
update swift ref.
Merge pull request #416 from LipuFei/update-win-build

Update build scripts for Windows