Update the metadata cursor implementation.

Move it into it's own cursor implementation, add a special search
routine that can search the metadata for the metadata table.

This is prototype code - I haven't tested the new functionality yet.
Fix build warning.
Further implementation of metadata cursors.
Minor fixes for metadata cursors.
Merge branch 'develop' into metadata-cursors

Conflicts:
	dist/s_string.ok
Add a test for metadata cursors, and a bit more implementation.
More metadata cursor implementation.

Copy keys in when required
Update test case.

Now next, prev and search should work.

Still need to implement search_near, test error conditions, and look for
memory leaks.
Merge branch 'develop' into metadata-cursors
Add ret to API_END.

refs #969
Merge branch 'develop' into metadata-cursors
Fix metadata cursor dup and search_near.
Update list utility to work with new metadata cursors.
Metadata cursor cleanup.
Update comments.
Update dump utility to use new metadata cursors properly.
Tidy up related to metadata cursors.
fix a comment typo
Merge pull request #910 from wiredtiger/metadata-cursors

Update the metadata cursor implementation.