'hg status -q' output skips non-tracked files.
The '-q' flag was ignored in status command. But this flag
can be used to hide non-tracked files in hg status output.
This small correction makes status command more general,
similar to 'svn status', where '-q' flag has the same effect.
The '-u' and '-A' flags have priority over '-q'.
A testcase and doc-string for status was extended to cover
'-q' flag.
% file replaced with directory
adding a
% should fail - would corrupt dirstate
abort: file 'a' in dirstate clashes with 'a/a'
% directory replaced with file
adding a/a
% should fail - would corrupt dirstate
abort: directory 'a' already in dirstate
% directory replaced with file
adding b/c/d
% should fail - would corrupt dirstate
abort: directory 'b' already in dirstate