Merge pull request #307 from Sayantan2048/bleeding-jumbo

bf-opencl code cleanups
Incremental: Correct progress for multiple nodes.
MPI: Tweaks for file locking problems during restore.
undrop: limit the length of password. (Fixes a crash.)
krb5: ensure that username and realm are non-empty. (Fixes SIGFPE.)
bitcoin format also works for litecoin wallet files!
Add support for cracking scrypt stuff
minor fixes for scrypt format
descrypt-opencl:code cleanup