Fix closing and reopning rqt_bag topic views

This addresses several bugs:
 * It wasn't possible to close topic views when running standalone
 * If topic views were closed (non-standalone), it wasn't possible to
   open them again

This also moves the logic for handling open/close interactions out of
the TopicMessageView class, where they might not always be called, and
into the owning class instead
Refactor graph backends into wrapper
Make DataPlot a proxy for its plot widget
Redraw after loading new data
Subscribe to any known topic

Fix _get_topic_type so that it can get the type of a topic that is subscribed to, even if it isn't published yet.
Update maintainership information of plugins I Authored and Maintain
Merge pull request #230 from trainman419/fix_bag_topic_close

Fix closing and reopning rqt_bag topic views
Merge pull request #233 from trainman419/plot_subscribed_topics

Subscribe to any known topic
clarify what should go into rqt_py_common
Add docstrings
Implement clear_values
Remove comment per discussion in #236
Merge pull request #237 from ros-visualization/clarify_py_common

clarify what should go into rqt_py_common
update changelogs
0.3.6
rqt_reconfigure: Fix bug in float range calculations

This only affected float parameters in which the minimum was well defined but
the maximum was infinite.
Merge pull request #241 from cottsay/groovy-devel

rqt_reconfigure: Fix bug in float range calculations
use queue_size for Python publishers only when available
Merge pull request #243 from ros-visualization/conditional_queue_size

use queue_size for Python publishers only when available
Merge pull request #236 from trainman419/py_common_plot

Document rqt_plot backend as public API