Prepare 0.8.4 -- 0.8.3 plus important bugfixes

I will make a [branch](https://github.com/obspy/obspy/tree/rc2_0.8.4) to cherry-pick commits in there. I went through the log since 0.8.3, these commits seemed most relevant.
It is probably safest to really only include 1-2 things, to not run into inconsistencies..

```
commit 3eabced2b693e3580479db79efbe0342701cdbfe
Author: Robert Barsch <barsch@egu.eu>
Date:   Wed May 1 14:26:36 2013 +0200

    fixing a failing import

commit e3f10bc160248f8d0d0adcb500646c213828d856
Author: Robert Barsch <barsch@egu.eu>
Date:   Wed May 1 14:20:08 2013 +0200

    all public C methods need to be listed in .def file for win

commit 342d86f07584ef6bd3c52dbe224bc478e2217325
Author: Lion Krischer <krischer@geophysik.uni-muenchen.de>
Date:   Mon Apr 29 10:27:41 2013 +0200

    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.

commit 1fb922ef8620cf026d7e50bb979b99916e889956
Merge: d5b6f19 f0f1832
Author: Robert Barsch <barsch@egu.eu>
Date:   Tue Feb 26 03:44:57 2013 -0800

    Merge pull request #521 from krischer/libmseed-2.10
    
    Update to libmseed 2.10

commit 9f352505b8183d99f991a5d972e0f928f7ca02da
Author: mbyt <random.seed@web.de>
Date:   Mon Jan 7 17:30:02 2013 +0100

    Adding msr_parse_selection to mseed win def file

commit f1cfbe61c18d7c42febefab202364c946247758f
Author: mbyt <random.seed@web.de>
Date:   Sun Jan 6 07:53:41 2013 +0100

    mseed: add msr_parse_selection to windows def file

commit 46a39e134ce3fa2474d5998a73d08c2c53f01531
Author: mbyt <random.seed@web.de>
Date:   Wed Dec 26 12:48:39 2012 +0100

    Bugfix for C files containing obspy in their name

commit a31f332cb711226ff951937f71ec80ae490e3737
Author: Robert Barsch <barsch@egu.eu>
Date:   Fri Dec 21 08:27:02 2012 +0100

    fixing incorrect entry point for obspy.db features

commit 6526c68db2e7f5d908bf07b6a266daddd938f785
Author: Robert Barsch <barsch@egu.eu>
Date:   Tue Dec 18 16:22:13 2012 +0100

    fixes #489

commit 73f2409457d5cf7db28d480c2e1f99630f86fd4e
Author: Robert Barsch <barsch@egu.eu>
Date:   Tue Dec 18 15:17:33 2012 +0100

    fixing download_url for dev version via easy_install
```