[RFC] shlex.split is bad for win32

[Alexander Belchenko]

In [1]: import shlex

In [2]: shlex.split(r'foo C:/bar/spam')
Out[2]: ['foo', 'C:/bar/spam']

In [3]: shlex.split(r'foo C:\bar\spam')
Out[3]: ['foo', 'C:barspam']

This affects some plugins, but more important: it affects `bzr diff 
--using xxx`

E.g. bzr diff --using "C:\Program Files\WinMerge\WinMergeU.exe" does not 
work, while bzr diff --using "C:/Program Files/WinMerge/WinMergeU.exe" 
does actually work.

Instead of shlex.split should be used Win32 API CommandLineToArgvW() 
function (http://msdn.microsoft.com/en-us/library/bb776391(VS.85).aspx)
This function is already using in win32utils:get_unicode_argv() function.

There is special function in commands.py

def shlex_split_unicode(unsplit):
     import shlex
     return [u.decode('utf-8') for u in 
shlex.split(unsplit.encode('utf-8'))]


So I think it should be platform dependent and use right method on 
win32. Right?

Dear plugin writers! Please use the function shlex_split_unicode in your 
plugins and never shlex.split directly. So once someone will fix its 
behavior re backslashes your plugin will work much better on Windows.
Thanks.