Fix flake8 for test_spectrogram.py
BUG: mseed, avoid pointer out of bound access

see #678
correcting type in readMSEEDBuffer

and refactoring, see #678
mseed: more verbosity, correcting reclen, tests

It was not possible specifying usefull reclens, trying to correct.

Adding tests related to see #678.

Adding more explicit logging to obspy-readbuffer.c to ease future
debugging, e.g.:
```
python -c "from obspy import read; read('/path/to/test.mseed', verbose=2)"

readMSEEDBuffer(): calling msr_parse with mseed+offset=58461152+0, buflen=8192, reclen=-1, dataflag=0, verbose=2
(null): Unpacking Steim-2 data frames
readMSEEDBuffer(): calling msr_parse with mseed+offset=58461152+4096, buflen=8192, reclen=-1, dataflag=0, verbose=2
(null): Unpacking Steim-2 data frames
```
Merge pull request #678 from mbyt/678

test_full_seed_with_non_default_dataquality failing with strange behavior
avoid some numpy warnings in tests, prevent masking of a tested warning
corrections for test failures

* remove checking for warnings in test_spectrogram. We compare the real
  result, which are the png's, which are correct. I think we should not
  test for other library warnings inside our tests. However, I did not
  trace back, why this warnings dissapeared.
* the test reference data of relcalstack are on the fly corrected for the
  previous buggy arctan call. arctan2 or np.angle need to be called, else
  the quadrant of the tan is not evaluated correctly. However, the
  correction in 2f9876d also removed the conjugate() / imag *= -1.0
  line, which I do not understand. Therefore, I removed it.
recuresively including data for "new" setup.py

* see #573
* also simplifying setup directory determination
adding docs dir, is needed for tests, see #573
Merge pull request #573 from mbyt/573

Version information broken
Fixing unintentionally corrupt files
Adding proper corrupt test file.
obspy-readbuffer.c: Pass the correct remaining buffer length to
msr_parser().

It expects only one record. Passing the correct remaining length enables
it to avoid overstepping the buffer's bounds. Also added a test that
every passed record is at least 256 bytes long - this is the smallest
possible record length.
This should fix the issue discussed in #678.
Using Python callbacks for logging within libmseed.

ms_log() will now properly raise warnings and errors. An issue is that
now everything with a level of >= 2 will be an exceptions and everything
below a warning. There is no lower info-like level. Thus it will either
be an exception or a warning. I think this is acceptable for almost all
use cases.
Adjusting logging levels.
Fixing the previous logging facility.

It is now able to distinguish between log messages, warnings, and
errors.
Adjusting log level.
Adjusting tests to new mseed logging.
Adding newline for the sake of consistency.
Stripping output originating in C