Add Mikrotik indexes

[willglynn]

This PR adds several Mikrotik indexes, causing the following changes:

• mtxrGaugeIndex

-mtxrGaugeValue{mtxrGaugeIndex="17"} 54
-mtxrGaugeValue{mtxrGaugeIndex="7101"} 45
-mtxrGaugeValue{mtxrGaugeIndex="7201"} 501
+mtxrGaugeValue{mtxrGaugeName="board-temperature1"} 45
+mtxrGaugeValue{mtxrGaugeName="cpu-temperature"} 54
+mtxrGaugeValue{mtxrGaugeName="jack-voltage"} 501

• mtxrNeighborIndex

-mtxrNeighborMacAddress{mtxrNeighborIndex="1",mtxrNeighborMacAddress="48:8F:5A:17:D6:14"} 1
-mtxrNeighborMacAddress{mtxrNeighborIndex="2",mtxrNeighborMacAddress="AC:CC:8E:F7:DE:6B"} 1
+mtxrNeighborMacAddress{mtxrNeighborIpAddress="172.16.4.10",mtxrNeighborMacAddress="48:8F:5A:17:D6:14"} 1
+mtxrNeighborMacAddress{mtxrNeighborIpAddress="172.16.4.30",mtxrNeighborMacAddress="AC:CC:8E:F7:DE:6B"} 1

• mtxrOpticalIndex

-mtxrOpticalSupplyVoltage{mtxrOpticalIndex="9"} 3289
-mtxrOpticalTxPower{mtxrOpticalIndex="9"} -6343
-mtxrOpticalWavelength{mtxrOpticalIndex="9"} 131000
+mtxrOpticalSupplyVoltage{mtxrOpticalIndex="9",mtxrOpticalName="sfpplus1"} 3289
+mtxrOpticalTxPower{mtxrOpticalIndex="9",mtxrOpticalName="sfpplus1"} -6305
+mtxrOpticalWavelength{mtxrOpticalIndex="9",mtxrOpticalName="sfpplus1"} 131000

• mtxrPOEInterfaceIndex

-mtxrPOEStatus{mtxrPOEInterfaceIndex="1"} 2
-mtxrPOEStatus{mtxrPOEInterfaceIndex="2"} 2
-mtxrPOEStatus{mtxrPOEInterfaceIndex="3"} 5
+mtxrPOEStatus{mtxrPOEInterfaceIndex="1",mtxrPOEName="ether1"} 2
+mtxrPOEStatus{mtxrPOEInterfaceIndex="2",mtxrPOEName="ether2"} 2
+mtxrPOEStatus{mtxrPOEInterfaceIndex="3",mtxrPOEName="ether3"} 5

• mtxrPartitionIndex

-mtxrPartitionSize{mtxrPartitionIndex="1"} 1024
+mtxrPartitionSize{mtxrPartitionIndex="1",mtxrPartitionName="part0"} 1024

I opted to drop the index where it appears likely to change across reboots and leave the index otherwise.

[SuperQ]

This needs a DCO sign-off. You can use git commit -s --amend to add it.

Dropping source indexes is more about uniqueness. If there could be duplicates of a metric value in the new index, you want to keep the source indexes.