Ensure that the WT_CURSOR::uri field matches open_cursor URI.

Since we document that is how it works.
Fix which URI is used by schema truncate.
Return error from cursor open.
Merge branch 'develop' into cursor-uri-protect
Trivial simplification, we don't need a local variable.
Don't ignore error return from WT_CURSOR.close (it might be a panic).
Merge pull request #1235 from wiredtiger/cursor-uri-protect

Cursor uri protect