Catalog.plot(): add image tests
Catalog.plot(): more examples in API docs
install basemap in travis for image tests
Merge pull request #753 from megies/event_plot_refactor

Catalog.plot() refactoring
fix one catalog plot image test
Merge remote-tracking branch 'upstream/master' into station_plots_master
inventory/network: response plots
stations plots: change kwarg order (like in all Clients): "location" before "channel"
station: add methods `copy()` and `is_active()` to BaseNode class
station objects: add .select() method (returning shallow copies)
bode plots: add option for time constraints
refactoring/docstrings
refactoring
minor bugfix
basemap plot: slight adjustments to "local" projection

- adjust axes for ticklabels
- adjust basemap region (width/height) to match figure aspect ratio
  (avoids squishy axes with large empty spaces around it)
basemap plot: colorbar option to force it on/off manually
Inventory/Network: Location preview plots + image tests
bode plots: add show/outfile options, add image tests
bugfix
bode plot tests: suppress np warnings and matplotlib warnings during plotting