Fix file-changed-to-dir and dir-to-file commits (issue660). Allow adding to dirstate files that clash with previously existing but marked for removal. Protect from reintroducing clashes by revert. This change doesn't address related issues with update. Current workaround is to do "clean" update by manually removing conflicting files/dirs from working directory.

adding base
abort: qdelete requires at least one revision or patch name
abort: cannot delete applied patch c
Now at: b
a
b
a
b
series
status
Now at: a
a
b
series
status
1 [mq]: a
0 base
abort: cannot delete revision 3 above applied patches
f
4 [mq]: f
3 [mq]: e
2 [mq]: d
1 [mq]: a
0 base