sort: allow arbitary attributes
Speedup mchedr test.

- Read the mchedr catalog file only once (using setUpClass());
- Write QuakeML file only once.
test_mchedr: alt approach compatible with py2.6

...but uglier!
Reduce the number of phases in mchedr.dat

In order to sppedup test_mchedr.py
Merge pull request #693 from claudiodsf/speedup_pde_test

Speedup mchedr test.
minor helpstring fix
correcting method signature of c_sac_taper

* adding also docstring
* as this was really misleading before, I classify this as a bug and not as
  a refactoring and do no deprecation
failing test for #695
fixes #695, also avoid code duplication in checking data input when
setting Trace.data
minor cleanup for preview generation, needed to make tests pass again
(avoid intermediate step of setting multi-dimensional array, see #695)
Merge pull request #695 from obspy/695

Prevent Trace initialization from numpy arrays with ndim>1
attach response information to example stream
more flexibility in Response.get_evalresp_response

- possibility to specify choice of output units ("VEL", "ACC", "DISP")
  as supported by evalresp
- possibility to specify start/stop stages for deconvolution
Trace: new deconvolve() method (logic based on simulate() with less
cluttered options) to remove instrument response based on
new Response object introduced with obspy.station
Added support for gain only blockettes
Gain only stage now works for the response calculation.
New context manager to catch the output.

This variant does not leak file descriptors.
Nested with does not work with Python 2.6.
Merge pull request #698 from obspy/catchoutput_cm

New context manager to catch the output.
Merge branch 'master' into station2