TestKillRestartMulti: A map named undoLog-1 already exists

unused methods removed
min0r refactoring

Assorted minor changes

Undo log split to reduce contention

External authentication with datasource issue

update

This is bad, it opens up the whole new can of warms and need to be dealt with separately

Preserve original exception in CreateTable and AlterTableAddConstraint.

TableLink: column names are always case insensitive for MySQL

make beforeWrite() to call commit() instead of tryCommit() in case of unsaved memory churn

Address code review comments.

TransactionMap::sizeAsLong() optimized - temp map eliminated

1177 recover leak

Improve concurrency of connection pool with wait-free implement

Improve naming of the object id field in Prepared

Do not change ID of existing constraints in AlterTableAddConstraint