Lazy query execution support

TimestampWithTimeZone can not be bound

Clients that are still on Java 7 and can not use OffsetDateTime need a
way to bind TimestampWithTimeZone. Unfortunately TimestampWithTimeZone
can currently not be used as a bind parameter
The obvious way to bind TimestampWithTimeZone would be to use
PreparedStatement.setObject(int, Object). This does not work because
DataTye#convertTo currently does not check for TimestampWithTimeZone.

This commit fixes this by adding a check and conversion in
DataTye#convertTo and also adding a unit test.

#486: Support enum as user data type

Enum support

Fix headers format of MAVEN.md

Document recursive common table expressions

H2 supports recursive common table expressions. Unfortunately they are
not covered in the official grammar documentation so some people don't
know about it.

I had to reverse engineer the syntax by looking at the parser source so
it may contain errors. This commit does contain maybe not the greatest
documentation ever but I feel it's an improvement over the current
situation.

Fix fetch first rows only grammar

After some additional test for #476 and more checking with the source
code I found out that I make a mistake in the grammar. The
MySQL/Postgres and the Derby/Oracle syntax should be different
productions.

Document fetch first row(s) only