Chan-sccp-b release v4.2.3

Chan-sccp-b release v4.2.3

New Features in V4.2.3
 - Warning about use of ancient gcc compiler
 - New desktop/background images
 - New AMI Function:SCCPShowRefcount
 - Support for newer/future version of automake
 - Small size reduction of chan_sccp.so

Bug Fixes
 - Channel being left behind after hangup
 - Scheduled Hangup / Schedule Digit Timeout
 - Potential Deadlock Fallback Atomic Functions
 - MWI loosing track of new voicemails under certain circumstances
 - using gnu version of libiconv fixed
 - gen_sccp_enum improved / gnu awk extension dependency removed
 - set socket option should happen before binding to the socket
 - channel monitor/record handling fixed
 - Code cleanup / fixed memory leaks / fixed potential null pointer dereferences
 - Some smaller patches (Check ChangeLog for details)