ELF Tool Chain Code

* Added support for multiple ".debug_types" sections in one ELF object.
* Added API dwarf_next_types_section() which is used to iterate through
the ".debug_types" sections contained in the object. When libdwarf
is first initialized, an internal pointer points to the first
".debug_types" section. When dwarf_next_types_section() is called,
the internal pointer will point to the next ".debug_types" if more
than one such section exists.
API dwarf_next_cu_header_c() and some of the DIE APIs will operate
on the current ".debug_types" section the internal pointer points to.

Code cleanups in '''libdwarf''': move the `_dwarf_find_section()` helper
function to a more appropriate source location.

Reviewed by: kaiwang27
Ticket: #367

Turn on SVN keyword expansion.

Ticket: #348

Add `$Id$` keywords.

Ticket: #348

Cast size parameter to size_t for malloc/realloc where necessary.

Reported by: Richard Gorton

Changes to error handling [part 2 of 2].

* Change macro `DWARF_SET_ERROR()` to take a `Dwarf_Debug` debug context
in its 1st argument. If a `Dwarf_Debug` debug context is unavailable
at the point an error has to be recorded, we use NULL. Actual error
handling is implemented by function `_dwarf_set_error()`.
* Change a few internal helper functions to take an additional Dwarf_Debug
parameter, for use with `DWARF_SET_ERROR()`.
* Replace the redundant use of `DWARF_SET_ERROR()` in `_dwarf_die_add()`
with `assert()`s; parameters `cu` and `abbrev` cannot be NULL if control
has reached this function. While we are here make the function "static".
* Use `DWARF_SET_ERROR()` consistently after a failed called to
`_dwarf_attr_find()`.

Reviewed and revised by: kaiwang27

* Implement consumer de-initialization functions for each DWARF info type.
* Implement producer de-initialization functions for each DWARF info type.
* Call all the consumder de-initialization functions in _dwarf_consumer_deinit().
* Add _dwarf_producer_deinit().

Renamed DWARF_E_USER_CALLBACK to DW_DLE_ELF_SECT_ERR.

Ticket: #20

Renamed DWARF_E_MEMORY to DW_DLE_MEMORY.

Ticket: #20

Substitute DWARF_E_NONE with DW_DLE_NONE.

Ticket: #20