Added some periods to some comments and added an overload for operator<< for...

Added some periods to some comments and added an overload for operator<< for type Sequence so I can print out Sequences in debug statements.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173831 91177308-0d34-0410-b5e6-96231b3b80d8