Add test cases that compare the performance of the transitive_closure
virtual table again common table expressions for walking a tree.
Add a few more CTE test cases to closure.test.
Use an unsigned integer to accumulate the string hash.  Avoids compiler
warnings.
Add test cases for LIMIT and ORDER BY on recursive CTEs.
Fix harmless compiler warnings in the Tcl interface.
Select collation sequences for ORDER BY expressions attached to recursive CTEs in the same way as they are selected for other compound SELECT statements.
Fixes for various clang warnings.
Fix a problem causing SQLITE_OMIT_COMPOUND_SELECT builds to fail.
Fix some problems in test scripts. No code changes.
Fix (harmless) duplicate variable declaration.
Fix a problem in pagerfault.test causing an assert() to fail.
Update some requirements marks to conform with improvements
in the documentation.
Fix a couple of problems with new test scripts causing the permutations test to fail.
Minor bugfix in main.c so that the library builds with SQLITE_OMIT_WSD defined.
Bring in the latest updates from trunk.