obspy-runtests: check on module basis if tests can be run

this commit adds a mechanism to check in obspy-runtests on a module
basis if all tests of the corresponding module can be executed or if all
tests of the corresponding module should be skipped.

this also implements this check for obspy.seishub, such that all tests
will immediately be skipped (even doctests) if the server is not
reachable.  until now, an unreachable server resulted in long timeout
wait time due to doctest executing all tests even after first failures
(this behavior can only be altered with doctest.FAIL_FAST starting with
Python 3.4, unfortunately)
seishub: use timeout in all requests
evalresp: Fix realloc bug.

The return value of realloc is the possibly new pointer to the memory
block. Using the original pointer afterwards could be cause for a crash
if the reallocation caused the pointer to change.
evalresp: Fix "set but unused" warnings.
libtau: Expand tabs for less warnings.
libtau: Remove unused code that causes warnings.
evalresp: Remove unnecessary memset.

This memset is wrong since sizeof(pointer variable) is just the size of
a pointer, not the size of the buffer. Anyway, strncpy is going to
overwrite it.
evalresp: Fix some uninitialized variable.

There are more, but I don't understand the code enough to just blindly
set defaults. I really think this is quite fragile, and assumes all input
is well-formed.
mseed: Fix incorrect return value.

The return type is a pointer, so returning -1 is going to be bad...
libtau: Make precision conversions explicit.

This reduces a significant number of warnings. Many of these variables
are explicitly one type or the other, so I figure making the conversion
explicit will not harm anything.
libtau: Fix unused parameter warning.

I'm a bit surprised that this works, actually. I'm sure a C compiler
would have recognized this trick.
evalresp: Fix warnings about getcwd.

This code is one long filename/path away from a seg fault, though.
evalresp: Fix unused return value warnings.
evalresp: Fix parenthesis warning.

Since bitwise AND is lower precedence than addition, this actually
appears to be wrong. The two bytes would be added and then AND'd with
255, so the result is basically equivalent to one byte.
mseed: Fix signed/unsigned comparison warning.
signal: Remove unused parameters to generalizedBeamforming.
evalresp: Fix signed/unsigned comparison warning.
mseed: Fix strict prototypes.

I noticed these additional warnings on Travis. A C function that takes
no parameters should use (void), not (). The logging functions are
documented as taking const char*, but it's not written that way.
evalresp: Fix strict prototypes.

Also, remove old-style parameter declarations. They're not even ANSI
standard.
Merge branch 'master' into warning-cleanup

Conflicts:
	obspy/signal/src/evalresp/evresp.c