Add warnings for bad combinations of Device and Interface. On Linux, the name of the tun/tap interface can be set freely. However, on most other operating systems, tinc cannot change the name of the interface. In those situations, it is possible to specify a Device and an Interface that conflict with each other. On BSD, this can cause $INTERFACE to be set incorrectly, on Windows, this results in a potentially unreliable way in which a TAP-Win32 interface is selected.
Modernize the build system. Recent versions of autoconf and automake were giving a lot of warnings. This is sort of a backport of similar build system changes from the 1.1 banch: - Fix all autoconf/automake warnings. - Merge lib/ into src/. - Don't use symlinks for device.c any more, but use automake conditionals. - Use explicit paths to local header files. - Get rid of alloca.c/malloc.c/memcmp.c/realloc.c.