see #548, different way to handle multiple sampint

this should just show an alternative possibility to handle multiple
sampling rates for obspy-scan.
GSE2 replacing fgets calls to function pointer

* this will allow direct reading of string buffers from python
GSE2: Adding python callback for buffer reading

* also added test on null pointer, could not avoid to the printing of an
  error to stdout
adding decomp_6b_buffer to windows def file
Using proper malloc() while writing MSEED data.

The datasamples pointer in writeMSEED() is now filled with a proper
malloc call and not the old and hackish resizing approach. Now also runs
on Python 2.7.4. Fixes #551.

Also changed the MSTraceGroup to a simple MSTrace as it is only used one
trace at a time.

Requires recompilation of the shared obspy.mseed library.
Fixing confusion of numpy.string_ dtypes.

test_writeAndReadDifferentEncodings() now works across different NumPy
versions. Fixes #552.

Conflicts:
	obspy/mseed/tests/test_mseed_reading_and_writing.py
Bugfix for waveform plotting.

There a slight error in the data binning. It always occurred but only
manifested for certain data lenghts. Also added a test for it.
stream.plot(): More fixes

Found another sample count that messes with the binning. This should
solve the issue.
fixing a failing import
all public C methods need to be listed in .def file for win
fixing incorrect entry point for obspy.db features
fixes #489

Conflicts:
	obspy/core/util/xmlwrapper.py
fixing download_url for dev version via easy_install
Small bugfix for blockette 60 initialization.
fixes #554
Replacing the numpy views with true type casts.

Views do not change the underlying data and thus do not work with
custom C code that expects raw data of the correct type.

Conflicts:
	obspy/core/tests/test_stream.py
adding missing import
adding a missing import
remove darwin_compiler_fixup (missing in newer python 2.7
reverting commit 0ef60b8 as xml_doc gets closed too

Conflicts:
	obspy/core/util/xmlwrapper.py