Update README.md
fixing C coverage to run with numpy.distutils

When changing to numpy.distutil setup.py generation of c_coverage was
broken, see #562. This is fixed with this commit, by the following steps:
* introduce FFLAGS, CFLAGS do not work for numpy setup.py gfortran
* -lgcov needs to be linked explicitly for gfortran, adapting setup.py
  with an environment variable switch to add gcov
* python setup.py clean --all develop does not clean up *.o *.so files any
  more. Therefore, handling cleanups explicitly in the script (maybe we
  should go for pip)
Merge branch 'master' into 562
Merge pull request #562 from mbyt/562

C Coverage does not work (was: libtau_Linux_32bit_py27.so: undefined symbol: __gcov_merge_add)
aborting C gse2 decompression when n_samps == 0

reading gse2 files with n_samps = 0 will directly lead to segmentation
faults. Therefore, raising an Exception if that happens (see #538).
Even better handling for corrupt gse2 header.

Let the checksum detect the error when applied to a zero length array,
that's what a checksum is for, see #538.
correcting test file name

see #538
Merge pull request #538 from mbyt/538

obspy.core.read() no return from function when GSE2 chksum is wrong
Update of the SEEDManual_V2.4.pdf to the latest version of August 2012
Merge pull request #577 from bonaime/master

Update of the SEEDManual_V2.4.pdf to the latest version of August 2012
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.
arclink: check times in getInventory on channel level instead of
location level (i.e. on downmost level). this can help with faulty
location specifications around OK channel specifications. (see #586)
update old ObsPy version number use in two places
Changelog for 0.8.4
deb: manually remove one .gitignore during packaging

no idea why it gets included in the package building process in the
first place. several other .gitignore files get excluded automatically.
Throw verbose exception if no data has been added before plotting
Merge pull request #591 from bmorg/ppsd_plot_exception

Throw verbose exception if no data has been added before plotting
quakeml: reset patched RelaxNG schema

 - official version again (which has been fixed)
 - basically QuakeML-RT tags are now allowed as valid foreign tags
   (as is tolerated by QuakeML developers)
deb packaging: avoid problems/workaround with https and SSL