Extend osgar.logger with --stream-format option

[m3d]

choices ['index', 'name', 'full'] defaulting to index

---

My motivation is to replace:

python -m osgar.logger ~/git/osgar-apps/lidarroad/toDel.log --stream platform.manual platform.brakes | tail -15
0:16:46.752133 4 False
0:17:19.413129 7 True
0:17:20.230240 4 True
0:17:20.462803 7 False
0:17:20.513865 7 True

with

(python) md@md-ThinkPad-P50:~/git/osgar$ python -m osgar.logger ~/git/osgar-apps/lidarroad/toDel.log --stream platform.manual platform.brakes --stream-format name | tail -15
0:16:46.752133 manual False
0:17:19.413129 brakes True
0:17:20.230240 manual True
0:17:20.462803 brakes False
0:17:20.513865 brakes True
0:17:20.711501 brakes False

or

(python) md@md-ThinkPad-P50:~/git/osgar$ python -m osgar.logger ~/git/osgar-apps/lidarroad/toDel.log --stream platform.manual platform.brakes --stream-format full | tail -15
0:16:46.752133 platform.manual False
0:17:19.413129 platform.brakes True
0:17:20.230240 platform.manual True
0:17:20.462803 platform.brakes False
0:17:20.513865 platform.brakes True
0:17:20.711501 platform.brakes False

[m3d]

I guess there are no complains as the basic (default) functionality remains the same. Later I would change the default, in particular if you select two and more streams that they would be distinguish rather by name than by index ... but that is for the future. My main motivation for merge is potential conflict with the bigger PR - #1083