.removeEmptyCol: Search for (empty) columns conaining only entries defined in 'searchFields' and remove such columns
Description
This function aims to search for (empty) columns conaining only entries defined in 'searchFields' and remove such columns.
If 'fromBackOnly' =TRUE .. only tailing empty columns will be removed (other columns with "empty" entries in middle will be kept).
If ''=TRUE columns containing all NAs will be excluded as well
This function will also remove columns containing (exculsively) mixtures of the various 'searchFields'.