GH-80 Provide inferred return type from aggregate function output

Add ECLFuncion "returnsSameAsArgumentType" property
Add HPCCColumMetadata default decimalDigits and columchars
HPCCColumMetadata extracts column size, decimaldigits and/or columchars from
incoming ECLType string.
Therefore HPCCColumnMetaData ctor doesn't require valid sqltype
HPCCJDBCUtils TRAILINGNUMERICPATTERN specifies two new groups in order to easily extact n_y information
Implements ResultSetMetaData getPrecision and getScale

Signed-off-by: Rodrigo Pastrana <Rodrigo.Pastrana@lexisnexis.com>