Removing all dirty 'using namespace std' that were used as C++ library compatibility work-around

libuavcan/src/driver/uc_can.cpp

@@ -59,8 +59,6 @@ bool CanFrame::priorityHigherThan(const CanFrame& rhs) const
 #if UAVCAN_TOSTRING
 std::string CanFrame::toString(StringRepresentation mode) const
 {
-    using namespace std; // For snprintf()
-
     UAVCAN_ASSERT(mode == StrTight || mode == StrAligned);
 
     static const unsigned AsciiColumnOffset = 36U;

libuavcan/src/transport/uc_frame.cpp

@@ -198,7 +198,6 @@ bool Frame::operator==(const Frame& rhs) const
 #if UAVCAN_TOSTRING
 std::string Frame::toString() const
 {
-    using namespace std; // For snprintf()
     /*
      * Frame ID fields, according to UAVCAN specs:
      *  - Data Type ID

libuavcan/src/transport/uc_outgoing_transfer_registry.cpp

@@ -12,7 +12,6 @@ namespace uavcan
 #if UAVCAN_TOSTRING
 std::string OutgoingTransferRegistryKey::toString() const
 {
-    using namespace std;
     char buf[40];
     (void)snprintf(buf, sizeof(buf), "dtid=%u tt=%u dnid=%u",
                    int(data_type_id_.get()), int(transfer_type_), int(destination_node_id_.get()));

libuavcan/src/transport/uc_transfer_buffer.cpp

@@ -14,7 +14,6 @@ namespace uavcan
 #if UAVCAN_TOSTRING
 std::string TransferBufferManagerKey::toString() const
 {
-    using namespace std; // For snprintf()
     char buf[24];
     (void)snprintf(buf, sizeof(buf), "nid=%i tt=%i", int(node_id_.get()), int(transfer_type_));
     return std::string(buf);

libuavcan/src/uc_data_type.cpp

@@ -111,7 +111,6 @@ std::string DataTypeDescriptor::toString() const
     }
     }
 
-    using namespace std; // For snprintf()
     char buf[128];
     (void)snprintf(buf, sizeof(buf), "%s:%u%c:%016llx",
                    full_name_, static_cast<unsigned>(id_.get()), kindch,