TWiki::UI::Upload upload command handler.
This method is designed to be
invoked via the TWiki::UI::run method.
Attach a file to a topic. CGI parameters are:
 filename  | 
			Name of attachment | 
 skin  | 
			Skin(s) to use in presenting pages | 
upload command handler.
This method is designed to be
invoked via the TWiki::UI::run method.
CGI parameters, passed in $query:
 hidefile  | 
			if defined, will not show file in attachment table | 
 filepath  | 
			|
 filename  | 
			|
 filecomment  | 
			Comment to associate with file in attachment table | 
 createlink  | 
			if defined, will create a link to file at end of topic | 
 changeproperties  |