Broken handling of single-line messages with a tag block

[hogend]

Single-line messages are never parsed because of

tag_block.py: 147:
if sentence_num == 1:
self.groups[group_id] = {
'line_nums': [self.line_num],
'lines': [line],
'matches': [match],
'times': [time],
}
return

i.e. sentence_num == 1 always returns and the subsequent decoding code is unreachable.

Suggested fix:
if sentence_num == 1:
self.groups[group_id] = {
'line_nums': [],
'lines': [],
'matches': [],
'times': [],
}

then the data will be appended and, if sentence_num == sentence_total, decoded.