Add inline functions for readFile and writeFile for std::string

Fix portability problem due to == test

Add --disable-doc option

Improve the treatment of single line comment.

The "test" command, as well as the "[" command, are not required to know
the "==" operator. Only a few implementations like bash and some
versions of ksh support it.

When you run "test foo == foo" on a platform that does not support the
"==" operator, the result will be "false" instead of "true". This can
lead to unexpected behavior.

Make including library easier

libconfig can now be built by including with eg. add_subdirectory
directly, without changing compiler flags

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>

Some changes for CMakeLists.txt - one bug-fix included

Setting this define makes that

    #include <stdlib.h>

does nothing (because of the include-guard). But this file
is needed for free() and realloc() and others.

The cmake built-in variable BUILD_SHARED_LIBS
does exactly what LIB_TYPE was used for. Switching between
SHARED and STATIC library-builds.

Fixed an issue causing build to fail on OSX 10.12.

#96 : fix lib/CMakeLists.txt, add wincompat.c.

Added optional method chained interface

AM_CONFIG_HEADER is deprecated

configure cmake

Safely handle escape sequences

And accompanying tests

fixed from PVS-Studio