Improve documentation of window and some other functions

Fix window frame problems

New tests, reimplemented EXCLUDE clause, and assorted changes

MSSQLServer compatibility enhancements

Extend dictionary with `discard`, `enhancements` and `nolock` terms.

Adjust style and remove the `SQLServerSample` as it seems redundant with the
unit test present.

Add TransactionStore to MVStore jar

Add a dedicated example for `MSSQLServer` compatibility mode, that
shows all DBMS-specific features in a central, user-friendly place.

Add support for `create table test(id int primary key identity)` statements,
which are common in the SQLServer world.

Ignore table hints (e.g. "SELECT * FROM table WITH (NOLOCK)"), that form a
valid expression in SQL Server.

Reference:
https://docs.microsoft.com/en-us/sql/t-sql/queries/hints-transact-sql-table?view=sql-server-2017

Update Maven build instruction and fix some problems