first implementation to limit column list correctly
Inital version to support GROUP_BY view.
Limitations:
All columns used in GROUP_BY view need to be present in REPORT view also.
Columns used in IR link are now excluded.(Resolves #5)
Filters on columns which are not defined in the IR anymore are now skipped when printing headers. (Resolves #6)
Merge pull request #7 from commi235/issue_05

Issue 05