Fix Issue 10607 - DirEntry has no constructor

http://d.puremagic.com/issues/show_bug.cgi?id=10607

Fixes:
auto a = DirEntry("path"); //Correctly works

Simplified code a little bit (Axed _init)

Improved FileException usage
Fixing some un-necessary calls to text. Fix comment.
Fix Issue 10621 - dirEntry is (now) useless
Fix typo in xformat doc
Merge pull request #1407 from monarchdodra/DirEntry

Fix DirEntry string construction and CopyContruction