Added some missing issues to the c++1y status page, and put in hyperlinks for the papers.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188387 91177308-0d34-0410-b5e6-96231b3b80d8
Fix signed/unsigned warnings when building libc++ in C++14 mode

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@188395 91177308-0d34-0410-b5e6-96231b3b80d8