MQTT input does not handle certain characters in topic names

[borpin]

A topic of emon/xiaomi/4c:65:a8:d9:59:1a/battery results in a new input being created with every data item via MQTT.

ref https://community.openenergymonitor.org/t/delete-multiple-input-nodes-100s/9034

[borpin]

Merge of #1156 solves the specific case of colons, but a check is required to see if there are other characters that could cause issues.

[TrystanLea]

Here's the result with your example above and the latest topic mapping:

Then with:

emon/xiaomi/4c,65*a8/d9^59;1a/battery

[borpin]

Ah Ok great. Cheers.