Added new labels for use in displayprompt

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5536 43c1dc8c-776e-4df2-8ef1-6e829299be21
Replaced string based SKINNY_DISP_URGENT by embedded SKINNY_DISP_FLASH for urgent calls

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5537 43c1dc8c-776e-4df2-8ef1-6e829299be21