idc.AskFile does not set filter.

[GoogleCodeExporter]

idc.AskFile is documented to set a filetype mask.
however, it is using idaapi.askfile_c and not idaapi.askfile2_c, and sets the 
default file path and not a mask.

Original issue reported on code.google.com by [email protected] on 31 Mar 2015 at 10:10