Added DW_PERCENT_INDETERMINATE which can be passed to dw_percent_set_pos() to show a rotating or otherwise indeterminate percent bar on supported platforms. Platforms which don't support it will either show no progress or potentially growing and contracting progress in the future if that doesn't look too weird. Committed from Windows so may be fixes coming for the other platforms soon.

This is a file just to keep this directory in existance in CVS.