Added scaffolding for velocity mode

Added records to support detection of the current operation mode
(position or velocity), whether one is allowed to change between the two
and a record to actually change between the two. Also added a
doMoveVelocity method which should be implemented by derived drivers if
they support velocity mode.

db/sinqMotor.db

@@ -347,3 +347,37 @@ record(waveform, "$(INSTR)$(M):EncoderType") {
     field(NELM, "80")
     field(SCAN, "I/O Intr")
 }
+
+# Motors can operate either in position mode (0) or velocity mode (1). If the
+# mode is stored within the controller, the driver writes the corresponding mode
+# value into this record. If not, motors are always assumed to operate in
+# position mode.
+record(longin, "$(INSTR)$(M):Mode")
+{
+    field(DTYP, "asynInt32")
+    field(INP,  "@asyn($(CONTROLLER),$(AXIS)) MOTOR_MODE")
+    field(SCAN, "I/O Intr")
+    field(PINI, "NO")
+    field(VAL, "0")
+}
+
+# Motors can operate either in position mode (0) or velocity mode (1). If it is
+# possible to switch between the two, this record has a value of 1, otherwise
+# its value is 0.
+record(longin, "$(INSTR)$(M):CanSetMode")
+{
+    field(DTYP, "asynInt32")
+    field(INP,  "@asyn($(CONTROLLER),$(AXIS)) MOTOR_CAN_SET_MODE")
+    field(SCAN, "I/O Intr")
+    field(PINI, "NO")
+    field(VAL, "$(CANSETMODE=0)")
+}
+
+# Set the operation mode of the motor to position mode (0) or velocity mode (1).
+# If CanSetMode is 0, the mode cannot be changed and writing to this record
+# will have no effect.
+record(longout, "$(INSTR)$(M):SetMode") {
+    field(DTYP, "asynInt32")
+    field(OUT, "@asyn($(CONTROLLER),$(AXIS),1) MOTOR_SET_MODE")
+    field(PINI, "NO")
+}