quake ML validation using relaxNG schema

- validation now actually meaningful ;)
- two minor modifications from current official QuakeML 1.2 relax NG
- deactivating default stdout printing in validate routine, I would not
  expect a basic check routine that returns True/False to print messages
adapt two tests to be valid QuakeML
workaround for #559
changelog for quakeml validation
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.
Reverting whitespace removal within libmseed
Better error msg for test_writeAndReadDiff...()

Eases debugging.
Fixing confusion of numpy.string_ dtypes.

test_writeAndReadDifferentEncodings() now works across different NumPy
versions. Fixes #552.
PEP8 for obspy.mseed
Merge pull request #560 from megies/quakeml_validation

Quakeml validation
signal, template cross correlation: handling some edge cases
seishub client getKML: handle events w/o lat/lon