This creates a "document" class with only user-facing document state (no parser internals).
- document: user-facing document state
- document::iterator: iterator (equivalent of ParsedJsonIterator)
- document::parser: parser state plus a "docked" document we parse into (equivalent of ParsedJson)
Usage:
```c++
auto doc = simdjson::document::parse(buf, len); // less efficient but simplest
```
```c++
simdjson::document::parser parser; // reusable parser
parser.allocate_capacity(len);
simdjson::document* doc = parser.parse(buf, len); // pointer to doc inside parser
doc = parser.parse(buf2, len); // reuses all buffers and overwrites doc; more efficient
```
* Improving portability.
* Revisiting faulty logic regarding same-page overruns.
* Disabling same-page overruns under VS.
* Clarifying the documentation
* Fix for issue 131 + being more explicit regarding memory realloc.
* Fix for issue 137.
* removing "using namespace std" throughout. Fix for 50
* Introducing typed malloc/free.
* Introducing a custom class (padded_string) that solves several minor usability issues.
* Updating amalgamation for testing.