Necessary for RPM builds on RHEL5

Inspired by issue #173 I reviewed the
other function of the interface and
found a lot of problems with its
error handling.
Also made INI use collection public interfaces.

This patch eliminates the need to include
collection's private header and uses only
public interface.

The hashing logic was internal to the collection item.
But if someone wants to effectively deal with
the items and compare the property to a string
he should compare hashes first. But it was not possible
without the provided functions. As a result some
of the ELAPI modules had to take advantage of
knowledge of the item structure. This is bad.
So this patch lays foundation for refactoring
of the ELAPI code that was using internals of the item
directly (file_util.c mostly).
Also patch adds a unit test that was required for
testing new functionality and for ticket #83

This patch adds better options for
copying collections in flat mode.
It allows caller of the interface
to control prefixing of the fields
when one collection is appended to another.
It also avoids creating prefixes when the
collection is simply copied in flat mode.
Also for ELAPI I realized that the most efficient
way to deal with the "resolved" event
(event where all templeted values are actually replaced
with the real values) is to add a callback
capability to a copy collection function
so that the callback can be used to modify
the data (resolve it) while the copy operation
is in progress. This approach eliminates the need
for separate set of lookups after the event
is already copied.

This patch addresses several issues:
a) Adds capability to add or copy the collections
in flattened mode but construct names of attributes
in dotted notation. For example when you append collection
"sub" with items "foo" and "bar" previously you
could add them as "foo" and "bar" not you can
flatten them and the names will be "sub.foo"
and "sub.bar" this allows better processing of the
attributes in the elapi message.
b) Removes old implemntation of the
copy collection function.
c) Removes the col_set_timestamp,
this functionality has been moved to ELAPI
long ago.
d) Updates collection unit test.
e) Updates elapi to use new functionality
f) Updates elapi unit test
Have run under valgrind with no problems.