signal: Fix invalid write in arPick.

Fixes #825.
mseed: Fix possibly unterminated string.

The specified limit is for characters + NUL, but strncpy does not
NUL-terminate the destination if the source is longer than said limit.
The destination correctly contains enough room for the NUL, but does not
explicitly set it if strncpy overflows.
mseed: Correctly NUL-terminate some strncpy calls.

Since these inputs are user-provided, there's no guarantee they'd be
within the length limit, so it's prudent to explicitly NUL-terminate
them, since strncpy will not do so on overflow.
signal: Fix out-of-bounds read in arPick.

I don't know if this is correct or not, but it fixes a valgrind warning.

See #825.
mseed: add test file for so far unsupported SRO encoding in miniseed
Adding support for SRO encoded MiniSEED files
Adding some more miniseed encodings.
Added definitions of unsupported encodings.
Proper errors for reading miniseed files with unsupported
encodings.
Removing 'recinfo' argument from readMSEED().

Does not break any existing code and the speed gain is
minimal in any case.
Better handling of encoding during writing.

Some encodings cannot be written with libmseed. Now raises appropriate
errors.
Test that the correct exceptions are raised
Also test setting the encoding via the trace stats.
Added test for the GEOSCOPE16_4 format.

The file has been downloaded and binary patched to fix an obviously wrong
header value and to reduce the record length to 512 bytes.
Renaming test file
Adding test case for the SRO format
Compat for Python 2.6
Reworked the obspy.mseed documentation.
Added test for setjmp/longjmp issue
Adding test for the DWWSSN.

The test file is from IRIS and has been manually patched to have a
shorter record length.