[PDB] Partial resubmit of r296215, which improved PDB Stream Library.

This was reverted because it was breaking some builds, and
because of incorrect error code usage.  Since the CL was
large and contained many different things, I'm resubmitting
it in pieces.

This portion is NFC, and consists of:

1) Renaming classes to follow a consistent naming convention.
2) Fixing the const-ness of the interface methods.
3) Adding detailed doxygen comments.
4) Fixing a few instances of passing `const BinaryStream& X`.  These
   are now passed as `BinaryStreamRef X`.

llvm-svn: 296394
diff --git a/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp b/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
index 1843a3c..a7ba98d 100644
--- a/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
+++ b/llvm/tools/llvm-pdbdump/LLVMOutputStyle.cpp
@@ -450,7 +450,7 @@
     auto Blocks = File.getMsfLayout().StreamMap[SI];
     P.printList("Blocks", Blocks);
 
-    StreamReader R(*S);
+    BinaryStreamReader R(*S);
     ArrayRef<uint8_t> StreamData;
     if (auto EC = R.readBytes(StreamData, S->getLength()))
       return EC;
@@ -745,10 +745,10 @@
           public:
             RecordVisitor(ScopedPrinter &P, PDBFile &F) : P(P), F(F) {}
             Error visitUnknown(ModuleSubstreamKind Kind,
-                               ReadableStreamRef Stream) override {
+                               BinaryStreamRef Stream) override {
               DictScope DD(P, "Unknown");
               ArrayRef<uint8_t> Data;
-              StreamReader R(Stream);
+              BinaryStreamReader R(Stream);
               if (auto EC = R.readBytes(Data, R.bytesRemaining())) {
                 return make_error<RawError>(
                     raw_error_code::corrupt_file,
@@ -758,7 +758,7 @@
               return Error::success();
             }
             Error
-            visitFileChecksums(ReadableStreamRef Data,
+            visitFileChecksums(BinaryStreamRef Data,
                                const FileChecksumArray &Checksums) override {
               DictScope DD(P, "FileChecksums");
               for (const auto &C : Checksums) {
@@ -774,7 +774,7 @@
               return Error::success();
             }
 
-            Error visitLines(ReadableStreamRef Data,
+            Error visitLines(BinaryStreamRef Data,
                              const LineSubstreamHeader *Header,
                              const LineInfoArray &Lines) override {
               DictScope DD(P, "Lines");