Builders and security fix

• Added CharReaderBuilder and StreamWriterBuilder
  • See Advanced Usage in our docs.
  • These allow consistent configuration of CharReader and StreamWriter for users who require customization.
  • They will also let us add new features without breaking binary-compatibility.
  • If you are using operator<<(ostream, Json::Value) and operator>>(istream, Json::Value), you will not notice a change.
  • The old Reader and old Writers are deprecated, but still maintained.
• Fixed security hole.
  • A deeply-nested JSON input could cause a seg-fault.
  • The fix is imperfect. Please stop using the deprecated classes.
• Minor bug-fixes and enhancements, including:
  • -Wall -Wextra -pedantic for gcc
  • Minor formatting improvements, mainly to the deprecated StyledStreamWriter (which was the default for operator<<(ostream, Value).
• Reverted C++11 features.
  • We still use C++11 in cmake, but we are rebasing the v0.8.z branch (which is binary-compatible with the ancient sourceforge 0.6.0-rc2 release) in order to provide all the bug-fixes possible.
  • Going forward, we intend to follow the Apache versioning model for functional-, source-, and binary-compatibility.