and add  a another test case for datediff

Issue#458 TIMESTAMPDIFF YEAR fix

Rollback and delayed meta save.

"Unique index or primary key violation" in TestMvccMultiThreaded

Fixes h2database/h2database#458 TIMESTAMPDIFF()

by using reader-writer lock, reported issue #538

Fix for Issue #543

*Fixes the missing file tree.js in the web console

# Conflicts:
#	h2/src/docsrc/html/changelog.html

Support TIMESTAMP_WITH_TIMEZONE 2014 JDBC type

While we currently support TIMESTAMP WITH TIME ZONE and OffsetDateTime
the corresponding JDBC type TIMESTAMP_WITH_TIMEZONE(2014) is not
supported when calling PreparedStatement.setObject(int, Object, int).

Add DB2 timestamp format compatibility

Using a dash to separate date and time

Implement right-padding of CHAR(N) datatype in PostgreSQL mode

When using CHAR(N) in PostgreSQL any inserted value smaller than N
characters will be right-padded with spaces to fill all N characters.
See: https://www.postgresql.org/docs/9.1/static/datatype-character.html

This change adds an additional Mode.padFixedStrings and set it to true
in the PostgreSQL Mode. Any value converted to a ValueStringFixed at
INSERT will be right-padded with spaces.

For additional infos see the H2 Google Groups post:
https://groups.google.com/forum/#!topic/h2-database/Luaxdrl137Y

Issue#479 Enhanced tests - removed comment about parameters not working for common table expressions - they appear to me to be working

Fix Travis Builds.

Issue#479 Allow non-recursive CTEs (WITH statements)