typo in merge

and making them sort-of regular functions makes it easier to allow
overriding them

Charset collation

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

Refactor synonym implementation

Remove most of the abstract methods in AbstractTable. Instead add abstract resolve()/asTable() method, that return the backing table.

Issue#556 close connections in tests (at least in case of successful execution)

unfortunately can't enable this yet - I'm pretty sure the FileSystem
side is fine, but the MVStore obviously needs more sync points somewhere

update docs to match code

this limit applies to both 32 and 64-bit VMs

Issue#556 tst fix

Update synonym implementation

Issue#560 thread leak

Check for unsupported column types in PostgreSQL mode

* Close connections in test
* Call updateMeta in CreateSynonym to make sure changes get persisted
* Drop synonym when the backing is table is dropped to fix ticket #556

eliminate memory estimations for "mem:" case

Add entries for Generic cloud and datawarehouse databases.

This patch adds entries for Generic database entries for cloud
and data warehouse databases. This is solely for convenience
for people using the web server as a convenient frontend for
SQL database.

Conventional RDBMS databases moved into the cloud:

 - Azure SQL (Microsoft, based on SQL Server)
 - Redshift (Amazon, based on PostgreSQL 8)

(Note: Redshift can also use a PostgreSQL driver but the
Redshift driver has significantly better performance.)

Cloud-native databases:

 - Hive 1
 - Hive 2

(Note: hive may be run on a vanilla Hadoop cluster, a Cloudera
cluster, or a Hortonworks cluster. The last two products may
offer custom JDBC drivers.)

(Note: this patch does not address Kerberos authentication
or SSL encryption.)

Data warehouse databases:

 - Impala
 - Snowflake
 - Teradata

Impala is part of the Hadoop ecosystem and provided by Cloudera.
Snowflake and Teradata are both commercial products.

Issue#549 Removed UNION ALL requirements for CTE