How to: add a new submodule

• add it in obspy.core.util.base.DEFAULT_MODULES (if tests can be run without internet access) or obspy.core.util.base.NETWORK_MODULES, so that obspy-runtests properly picks up the module's test suite
• add plugin entry points in setup.py (if it is a read/write plugin), so that read/read_events/read_inventory can look up the reading routine
• add docs module skeleton: misc/docs/source/packages/obspy.$SUBMODULE.rst, otherwise the submodule's documentation will not be built
• add to docs module overview: misc/docs/source/packages/index.rst, to get links to the submodule's documentation from the API front page
• add to KEYWORDS in setup.py