Change transaction IDs to 64-bits, remove code that deals with wrapping.
Back out one part of the previous change: new snapshot transactions should get an ordinary snapshot.
Update spelling list.
whitespace
Merge pull request #568 from wiredtiger/64bit-txnids

Change transaction IDs to 64-bits, remove code that deals with wrapping.
whitespace, fix a comment.
Fold some too-long lines.
The data-source cursor should have a reference to the session.
Fix a comment, txn IDs are 64-bit now.
Fix two issues with concurrent updates to skip lists.

First, we were retrying updates at the end of the skip list unnecessarily,
preventing the skip list from growing to multiple levels if there was a lot of
contention.  This turned skiplists into single-level linked lists in the worst
case.

Secondly, there was a race inside __wt_random, where the calculation could
race with updates to the shared state, leading to the sequence getting stuck
with zeros in the top or bottom 16 bits.
Make hot backups configurable in test/format.
Use read-uncommitted isolation for LSM worker sessions: they are always dealing with read-only files.
typo
The extension code needs to know what a transaction ID looks like,
replace wt_txnid_t with uint64_t.
Restore support for the wiredtiger_open() error_prefix configuration
string.

We now have up to 3 prefixes before the error message, turn it into a
comma-separated list (instead of the square braces we were using).

Closes #527.
Fix tests broken by fa40839097a97349f2831ba4a8d6f611c1e8e27d,
the error messages have changed, re-write the tests to expect
more general patterns rather than specific error strings.
Rename WT_CONNECTION.metadata_lock to WT_CONNECTION.checkpoint_lock.
Close #560.
fix a comment
Port to version 4.1 of the KVS library: lots of option changes, we can
now specify KVS_O_CREATE in all cases, and we have a real KVS_O_TRUNCATE
flag.
Rename uri_source to be wt_source, I think it's a bit cleaner than
talking about URIs.