WIP: fix decoding error

[faxm0dem]

this is an attempt at fixing #15

[faxm0dem]

Example output:

$ tmux2html 0 -o out.html --interval 0.2 --stream
Streaming (0.20s) to 20200204-qserv-install-3.html.
Press Ctrl-C to stop.
'utf-8' codec can't decode byte 0xba in position 129: invalid start byte
'utf-8' codec can't decode byte 0xba in position 129: invalid start byte
'utf-8' codec can't decode byte 0xba in position 129: invalid start byte
'utf-8' codec can't decode byte 0xba in position 129: invalid start byte
'utf-8' codec can't decode byte 0xba in position 129: invalid start byte

[faxm0dem]

Hi how can I help in this?