The charset collator allows sorting strings according to their binary representation in a given charset.

update docs to match code

this limit applies to both 32 and 64-bit VMs

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

use a set to keep track of the tables we need to analyze.
Perform the analysis after we have committed the main transaction, so we
don't hold table locks for any longer than necessary.

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.

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.

In order to make the doc generation for #476 working I had to fix some
errors in existing files. These cover

 - lines which are too long
 - incorrect indentation
 - invalid markup
 - missing javadoc

Since 1.4.177 H2 supports FETCH FIRST x ROW ONLY however this is not
reflected in the grammar documentation. This covers all the variations
of the syntax.

There are 3 `help.csv` but I believe I got the right one. Some of the
checked in files seem to have been automatically changed and I don't
know if I should have committed those as well.

Fixes #475

* Custom data types handler

* Updated doc, changelog, dictionary. Fixed review comment.

* Extended the custom types handler interface

* Fixed test

* Fixed review comments

* Added note on ABI stability of the feature to docs