Add TestStream.

Only tests ReaderBinary for now.
Stream/TestStream: Fix test, fix ReaderBinary.
Stream: Add ReaderBinary::ReadIntLe() and tests.
AllTests.py: Add TestStream
TestStream: Ensure 64bit constants treated as 64bit types.
Revert "TestStream: Ensure 64bit constants treated as 64bit types."

This reverts commit 28e328d859644b8ab97924732bc48e534690a1b5.
TestStream: Ensure 64bit literals treated as such. Take II :)