enhance doc for new kwargs in PPSD.__init__
add changelog for PPSD
add former binning value to test setup
change list to tuple
PPSD: add more infos in changelog
citation
citations with sphinx links in docstrings
Merge pull request #627 from trichter/ppsd_length+scale

PPSD scale of colorbar + adjustable FFT length
refactor image comparison

 - refactor NamedTemporaryFile to class instead of function factory
 - sublass it to ImageComparison
   - use with statement for cleaning up and optionally keeping testrun
     images
   - cleaner, shorter use in tests for image comparison
   - less duplicated code
image comparison: add option to obspy-runtests
data_used attribute for moment tensor.
Fixed typo in event.py
Improvements for picks and arrivals.

- Computation of backazimuth;
- Fixed station_code attribute;
- Arrivals are appended to origin;
- Removed a line I forgot at the previous commit :)
gitignore docs build directory
Removed unused imports.
correct backend check in runtests
Setting event.creation_info
try/except locale setting (for windows :P) and check backend
try/except locale setting (for windows :P)
Using smi: scheme for origin.earth_model_id

Not sure about all this "smi:" thing, though.