Beta uavcan servers fix

Stack trace:
Thread [1] (Suspended: Breakpoint hit.)
        12 __cxa_pure_virtual() libxx_cxapurevirtual.cxx:66 0x0808ca42
        11 notifyRxFrameListener() uc_dispatcher.cpp:216 0x080787ce
        10 uavcan::Dispatcher::spinOnce() uc_dispatcher.cpp:276 0x080787ce
        9 uavcan::Scheduler::spinOnce() uc_scheduler.cpp:196 0x0807b4e0
        8 spinOnce() abstract_node.hpp:88 0x080659fc
        7 spinOnce() node.hpp:132 0x080659fc
        6 UavcanNode::node_spin_once() uavcan_main.cpp:428 0x080659fc
        5 UavcanNode::run() uavcan_main.cpp:542 0x08065e74
        4 operator() uavcan_main.cpp:343 0x0806626a
        3 UavcanNode::__lambda0::_FUN() uavcan_main.cpp:343 0x0806626a
        2 task_start() task_start.c:138 0x08087720
        1 <symbol is not available> 0x00000000

Merged master_uavcan_modular src/modules/uavcan/

EKF Init fix

Fix coning handling in att_pos EKF. Fixes #2663

VTOL beta backport

Commander: Trigger preflight check on every reconnect, but not when armed. Make RC regained and other messages non-critical. Implement param reset method.