Added password masking using * as mask
Moved masking to GetPasswdMasked(). Removed char restrictions
Merge pull request #1 from amedeiros/feature/add-masking

Added password masking using * as mask
Support GetPasswdMasked on Windows.
Linux - Use go.crypto instead of importing C.
Doc update.
OSX - Back to C until Go 1.1

syscall.Termios not available on darwin until Go 1.1
OSX - use syscall.Termios in Go 1.1
Merge pull request #3 from jingweno/master

Use syscall.Termios for Go 1.1 on Darwin
Fix panic on windows, Issue #4.