Project tree: compare all items case-insensitively
The commit history is silent about the reason why folders and targets
are sorted case-sensitively, while files - case-insensitively. Sorting
all items case-insensitively is more consistent and potentially faster
std::stable_sort used by
QSortFilterProxyModel could start with a
closer-to-sorted range then.
This change has been discussed here: !176 (comment 131378) (the Case sensitivity section and the first Milian's reply to that comment).