include explicitly astobj2.h
free ast_variable associated to sccp_line_cfg
initialize flag_nodelay to 1
initialize flag_timeout at declaration time
initialize rtp to NULL

There was at least 1 case where the variable was used without being
initialized.
add static qualifier to functions
remove some unused parameters
enable more compiler warnings
allow a range to be specified in sccp-confgen
adjust message logging
minor, mostly cosmetic, changes
handle callforward migration
Merge branch 'review'