Change to CAN_MSG_VERSION_2 and elimination of linux/*.h headers from user space...

Layout of canmsg_t changed to CAN_MSG_VERSION_2, which is compatible
with PORT GmbH <http://www.port.de/> can4linux-3.1 implementation.
The driver and utilities can be compiled with old version,
if definition of CAN_MSG_VERSION_2 is commented out in
lincan/include/canmsg.h and canvca/libvca/canmsg.h headers.

The change from __u8 .. __u32 types to standard compliant u_int8_t .. u_int32_t
types has been required to eliminate linux/*.h files. This can make
problems to ancient Linux distributions and some workaround could
be necessary.