using TaskTreeView instead of QTreeView
cosmetics
AAA (Almost Always Auto)
moving TaskTreeItemDelegate to TaskTreeView
TaskTreeHeader
Globals have Cycle and Task models ownership
MainWindow transfered Cycle and Task models ownership to Globals
removed widget added by mistake
Column management
ROLE_VERTICAL_SECTION, model role for getting the header section of a row
*not tested* returning vertical section
setting column text alignment
commented code for displaying taskid as a row header