Drop thirdparty libraries and minor cleanups

With the implementation of the more elaborate benchmarking
suite at https://github.com/miloyip/nativejson-benchmark,
the thirdparty performance tests are superseded.

Clarify documentation on RemoveMember, EraseMember ordering

Use 'deprecated' instead of 'depreciated'

Issue123movesupport

Added MemoryPoolAllocator to GenericDocument moveunit tests. Added comment in GenericDocument move assignment operator explaining why the static_cast is needed to move the base class.

GenericValue: improve documentation for operator[]

GenericValue: improve operator[] disambiguation

In the original disambiguation fix for `GenericValue::operator[]` (#170),
the documentation has been missing, which led to quite badly rendered
Doxygen pages.

During a cleanup, I've realized that a much simpler disambiguation is
possible:

````cpp
  GenericValue& operator[](SizeType idx); // array
  template <typename T>
  GenericValue& operator[](T* name);      // object
````

This approach works, as non-template functions are preferred over
template functions.

In order to improve the error messages, the pointer type is restricted
to `(const) Ch`.

Update `tutorial.md` to drop the ambiguity warning.

Demonstrate CRTP in SAX example

Disambiguate GenericValue's [0] and ["string"]

Closes: https://github.com/miloyip/rapidjson/issues/142

.travis.yml: avoid Valgrind bug with '-march=native'

Fix MemoryStream::Peek() and add test for fix

Use -march=native for platform-specific optimizations

Add perf tests for EncodedInputStream and AutoUTFInputStream

Use predefined macros to enable SSE with gmake

MemoryStream::Peek() did not return '\0' if src_ == end_, but Peek() == '\0' is
used in parsing in the GenericReader. Without this change, parsing with
MemoryStream as the InputStream could result in a segmentation fault.

Correct `PushBack()` example

Fix small typo in the docs

turn implicit integer conversions into static_casts to avoid warnings

Alternative compilation fix for Solaris