Fix doxygen documentation

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5530 43c1dc8c-776e-4df2-8ef1-6e829299be21
Moved all the text based displayprompt messages to sccp_labels.h, making localization a little easier

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5531 43c1dc8c-776e-4df2-8ef1-6e829299be21