New interpolate() method for Stream and Trace objects.

Currently only wraps scipy.interpolate.interp1d but that already offers
a bunch of options.
doc: Use "int" for all integral types.

This is automatically linked by Sphinx to the Python type.
doc: Fix cross-references in obspy.station.
doc: Fix typos in StationXML.
doc: Fix indentation warnings in obspy.station.
doc: Fix cross-referencing in obspy.core.
doc: Fix cross-references in obspy.realtime.
doc: Fix cross-references in obspy.signal.
doc: Fix cross-references in waveform plugins.
doc: Fix some typos that break rendering.
doc: Fix cross-references in db/web clients.
doc: Fix exceptions in obspy.seedlink.
doc: Use "bool" for types exclusively.
doc: Fix some inconsistent type/param usage.
doc: Use "dict" instead of "Dictionary" for types.
doc: Use "float" instead of "Float" for types.
doc: Use "list[ of]" for types, exclusively.

This replaces "List", "List of", and "A list of".
doc: Remove periods from end of types.

The type is put in parentheses and periods look odd at the end.
doc: Fix unexpected indent errors in obspy.event.

Basically just adding empty lines before the bullet lists.
doc: Fix indentation errors in obspy.core.

All, that is, except obspy.core.util.misc.BAND_CODE, because I don't
even see a docstring for it, so I don't know why there are warnings
about it.