turn implicit integer conversions into static_casts to avoid -Wconversion warnings
Merge pull request #150 from TyRoXx/conversion_warnings

turn implicit integer conversions into static_casts to avoid warnings
Fix small typo in the docs
Merge pull request #154 from gadomski/doc-typo

Fix small typo in the docs
Update tutorial.md

Correct `PushBack()` example
Rename RAPIDJSON_NO_INT64DEFINE to RAPIDJSON_NO_STDINT

And revise the documentation.
Change int->int32_t and unsigned->uint32_t