Added expand/collapse all and restyled diff boxes

fixes #388
Positioned collapse/expand all button.
Updated CHANGELOG
do not trigger events when changed file is outside the current project (#397)
fixed some event handling
nit debug mode
history viewer now has close button (fix #401)
fix view authors of selection when selection ends on the beggining of the line (fix #398)
Merge remote-tracking branch 'FezVrasta/expandCollapseAll'
fix some history viewer bugs