Add docstrings
Implement clear_values
Remove comment per discussion in #236
Start adding plot plugin
Add new plot plugin to plugins.xml
Add empty but working plot view
Tinkering with plot plugin
Add topic to plugin view constructor
Initialize plot widget on startup
Pull in adwilson's matplot plugin
Use thread for loading bag files

The UI now appears immediately on startup, but still freezes for a bit
_after_ the bag file is done loading and has been added to the timeline.

Perhaps this is due to slow rendering?
bag plot mostly not working with rqt_plot backend
Add vline and limits to matplot and pyqtgraph
Actually use position when drawing vline
Unify autoscaling and autoscrolling
Make vline persist if a curve is removed
Actually use new limits methods
Fix import after rebase
More work on autoscaling