The doxygen files contained some deprecated values and typos.
This patch cleans them for all interfaces exposed by ding libs.

This patch fixes the doxygen warnings in the new interface.

Pointer was not initialized before being read.

This patch stops building interface docs for the old interface
and starts generating description for the new interface.

The three files in the patch implement the functions
of the new interface. It is mostly inspired by the old
interface except that the string value is replaced with
the value object that hides all the metadata about
the value itself. The main function to get value
now allows more than one value per key.

The search state allows one to search a configuration object
for the same key in the cases when a key permits more
than one value scattered across the config file.
The state needs to be stored, initialized and properly cleaned.

Some time ago I started the new INI interface
that exists in parallel to the existing interface
but uses value object to store value rather than just
strings. The header has all the details about the new
interface.

The patch adds function to get the length of
the concatenated value. It also adds a convenince
print function that is convenint in debugging
the values inside configuration object.
Patch also add checkes for input values
that can be passed by pointer.

The unit test was broken. The wrong function was used.
To make sure everything is correct I also added a convenience
function to print the internals if the file context object.
The unit test is fixed to use relative paths consitently.
Also added nice statements at the beggining and the end of
the unit test functions where they were missing.