Fix #289 negative zero roundtrip (double only)

Fix #288 double quote in unicode escape

Changing copyright holders, and details in license

fix zh-cn Doxygen generation for Travis CI

Localize documents to simplified Chinese

Fixes for GCC with -pedantic

tutorial.cpp: fix insitu parsing (closes #273)

The insitu parsing example in the tutorial is using a local char
buffer inside a nested scope.  After leaving the scope, the
resulting Document object still references this (now invalid)
memory locations.

Some compilers reuse this space on the stack for other local
variables later in the function, corrupting the original document.

Drop the local scope to extend the lifetime of the buffer.