[epg] adjust title to the left edge for the first items in timeline view

This adjust the title of the first item in EPG timeline view if you
scroll so it always starts at the left edge of the programme grid.
cosmetics: remove unnecessary NULL checks + code formatting
[gui] fix: reduce child item width by -10px every time you call EnlargeWidth()
cosmtics: fix comments
[confluence] fix: timeline item label overlapping