Makes type conversions explicit, if they alter a value

This switch is only active when making a release build.

This switch warns about missing prototypes. It does not warn if
functions are declared static. So this switch encourages the usage of
static whenever possible. This enables the compiler to perform inlining.

CMake: Option was not enabled by default as intended.
Makefile: Flags were not passed when building the tests

This can be disabled when the exporting of the targets causes problems.

This is for compatibility reasons with old CMake 2.8 versions.

The prior approach was exporting paths from the build environment.

Fix library and include paths in pkg-config, CMakeLists.txt and the
CMake config files.

These files will allow cmake based projects to find the
library using find_package(cJSON). If successful, they can
use CJSON_LIBRARIES and CJSON_INCLUDE_DIRS.

Other build systems can use a similar approach to pkg-config:
cmake --find-package -DNAME=cJSON -DCOMPILER_ID=GNU -DLANGUAGE=C  -DCMAKE_PREFIX_PATH=<path-to-non-sytem-installation-path> -DMODE=LINK

or with MODE COMPILE or EXISTS.

Turned off by default.