Fix 'sccp set hold on/off'. Extend command completion to include device completion after 'hold off'. Fix sscanf to inlude any character except '-' in the line part of 'SCCP/line98011-00001'.  (Fixes bug #207, reported by Dmitry)

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5043 43c1dc8c-776e-4df2-8ef1-6e829299be21