message: revert Buffer changes
diff: @@ -49,8 +49,6 @@ class Buffer {
  initWithNone();
  }
  - Buffer(char *data, uint64_t len) noexcept : _buffer((unsigned char*) data), _capacity(len), _size(len), immutable(true) {}
  -
  Buffer(Buffer const& that) : Buffer() {
  if (that._size > 0) {
  if (that._size > sizeof(_local)) {
  @@ -143,13 +141,11 @@ class Buffer {
  }
  void reset() noexcept {
  - checkImmutable();
  _size = 0;
  initWithNone();
  }
  void resetTo(ValueLength position) {
  - checkImmutable();
  if (position > _capacity) {
  throw Exception(Exception::IndexOutOfBounds);
  }
  @@ -158,13 +154,11 @@ class Buffer {
  // move internal buffer position one byte ahead
  inline void advance() noexcept {
  - checkImmutable();
  advance(1);
  }
  // move internal buffer position n bytes ahead
  inline void advance(std::size_t value) noexcept {
  - checkImmutable();
  VELOCYPACK_ASSERT(_size <= _capacity);
  VELOCYPACK_ASSERT(_size + value <= _capacity);
  _size += value;
  @@ -172,14 +166,12 @@ class Buffer {
  // move internal buffer position n bytes backward
  inline void rollback(std::size_t value) noexcept {
  - checkImmutable();
  VELOCYPACK_ASSERT(_size <= _capacity);
  VELOCYPACK_ASSERT(_size >= value);
  _size -= value;
  }
  void clear() noexcept {
  - checkImmutable();
  _size = 0;
  if (_buffer != _local) {
  delete[] _buffer;
  @@ -213,37 +205,33 @@ class Buffer {
  }
  inline void push_back(char c) {
  - checkImmutable();
  reserve(1);
  _buffer[_size++] = c;
  }
  void append(uint8_t const* p, ValueLength len) {
  - checkImmutable();
  reserve(len);
  memcpy(_buffer + _size, p, checkOverflow(len));
  _size += len;
  }
  void append(char const* p, ValueLength len) {
  - checkImmutable();
  reserve(len);
  memcpy(_buffer + _size, p, checkOverflow(len));
  _size += len;
  }
  void append(std::string const& value) {
  - append(value.data(), value.size());
  + return append(value.data(), value.size());
  }
  void append(Buffer<T> const& value) {
  - append(value.data(), value.size());
  + return append(value.data(), value.size());
  }
  // reserves len *extra* bytes of storage space
  // this should probably be renamed to reserveExtra
  inline void reserve(ValueLength len) {
  - checkImmutable();
  VELOCYPACK_ASSERT(_size <= _capacity);
  if (_size + len >= _capacity) {
  @@ -251,22 +239,9 @@ class Buffer {
  }
  }
  - void checkImmutable() {
  - if (immutable) {
  - throw Exception(Exception::BuilderNeedOpenCompound);
  - }
  - }
  -
  - bool isImmutable() const {
  - return immutable;
  - }
  -
  private:
  // initialize Buffer with a None value
  - inline void initWithNone() noexcept {
  - checkImmutable();
  - _buffer[0] = '\x00';
  - }
  + inline void initWithNone() noexcept { _buffer[0] = '\x00'; }
  // poison buffer memory, used only for debugging
  #ifdef VELOCYPACK_DEBUG
  @@ -278,8 +253,6 @@ class Buffer {
  #endif
  void grow(ValueLength len) {
  - checkImmutable();
  -
  VELOCYPACK_ASSERT(_size + len >= sizeof(_local));
  // need reallocation
  @@ -308,7 +281,6 @@ class Buffer {
  T* _buffer;
  ValueLength _capacity;
  ValueLength _size;
  - bool immutable = false;
  // an already allocated space for small values
  T _local[192];
  