Fixes #187.

Fixes #177.

Add new autotools-generated files to .gitignore

Fix unpack when mixing strict mode and optional keys

Three fixes for hashtable seeding on Windows

Thanks to Florian Weimer and Eric Sesterhenn for reporting, reviewing
and testing.

Fixes #147.

Replace strcpy with memcpy

Since len is known, the copy function does not need to check byte by byte
the end of the string.

Signed-off-by: Olivier Langlois <olivier@olivierlanglois.net>

Fixes #129.

Fixes #126.

BUGFIX: Compilation error with -DNDEBUG defined.

When building a "MinSizeRel" with CMake I get a compilation error in lex_unget_unsave. This is because assertions are turned off using -DNDEBUG:

```
/usr/bin/gcc  -DHAVE_CONFIG_H -fPIC -Os -DNDEBUG -Ijansson/build/include -Ijansson/build/private_include    -Wall -Wextra -Wdeclaration-after-statement -Werror -o CMakeFiles/jansson.dir/src/load.c.o   -c jansson/src/load.c
jansson/src/load.c: In function âx_unget_unsaveâjansson/src/load.c:256:14: error: variable â set but not used [-Werror=unused-but-set-variable]
cc1: all warnings being treated as errors
```

This will then remove the insert, which makes the "d" variable unused, which is treated as an error since we have -Wall set. We can't simply get rid of the variable either and put the strbuffer_pop call in the assert call, since it's a macro and would remove the call entirely. So I simply added a check for NDEBUG to fix it.

Adding option for MSVC for those who are linking statically.

Prevent compiler warning