This patch introduces an internal aggregate operator SELECT_SOME that
is automatically added to columns that are not in GROUP BY. It
"computes" some plausible value of the column (actually, last one
passed).
Along the way it fixes incorrect handling of HAVING being transferred
into WHERE, window function handling and a bit of other inconsistencies.
* toCppCode for ParseTree and TreeNode
* generated tree is compiling
* Put tree constructors into tests
* Minor fixes
* Fixed parse + some constructors
* Fixed includes, removed debug and old data
* Hopefully fix clang errors
* Forgot an override
* More overrides
Introduced fDecimalOverflowCheck to enable/disable overflow check.
Add support into a FunctionColumn.
Low level scanning crashes on medium sized data sets.
