New helper function.

Added a new helper function converting a vector of unit length given in
dip and azimuth to a unit vector in the vertical, south, east coordinate
system.
Added arbitrary dip/azimuth rotation.

Added a new function that allows to specify the orientation of each
component seperately with dip and azimuth. The components do not have to
be orthogonal to each other it should work nonetheless. The output are
three new arrays, always oriented Up, North, East
Added rotate2ZNE method to obspy.xseed.parser.Parser

This enable the (very basic) fully automatic rotation of arbitrarily
oriented components to ZNE. Also renames the channels.
Added test for the Parser rotation method.
Added test files.
Updating changelog
Better docstrings.
Merge branch 'master' into rotations.

Resolved conflicting CHANGELOG.
sort: allow arbitary attributes
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.
Merge branch 'master' into station2
Small changes to the unit handling
station: correctly read/write ResponseStages that only have StageGain
and nothing else (also adapt full random test to have one of those
minimal ResponseStages)
Sort all blockettes for one channel by the blockette number.

This should fix an issue with misordered SEED files.
Now sorting by stage sequence number and a custom blockette order.
Merge pull request #700 from obspy/resp_blkt_ordering

Ordering blockettes when RESP files are written.