Rewriter: Output RewriteRope contents efficiently

This avoids allocation of temporary std::strings for file contents, instead
writing chunks directly to the output stream.

The old character-based B-tree iterator remains intact for the time being.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@196119 91177308-0d34-0410-b5e6-96231b3b80d8
Re-enabled support for the Subjects for the weak attribute. This changes the diagnostic involved to be more accurate -- for C++ code, it will now report that weak applies to variables, functions or classes. Added additional test case for this.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@196120 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format vs plugin: bake clang-format.exe into the vsix

This makes the clang-format plugin self-contained. Instead of
requiring clang-format.exe to be available on the PATH, this
includes it in the plugin's installer (.vsix file) and runs it
from the install directory.

Differential Revision: http://llvm-reviews.chandlerc.com/D2281

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@196122 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a typo in a comment: expasion -> expansion

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@196123 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format vs plugin: use Alp's suggestion for getting the path

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@196124 91177308-0d34-0410-b5e6-96231b3b80d8