Added support for HSQL database. Revised dialects some more.

Added support for HSQL database. Revised dialects some more.

Moved CREATE TABLE and CREATE INDEX statement generation to the dialect.
Added DECIMAL(length, scale) support.
Improved automatic dialect detection.
Unspecified length string is now CLOB instead of TEXT.
Boolean now maps to BOOLEAN instead of BIT.
Expressions on unmapped fields will throw an IciqlException.
Improved exception reporting.