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.
signal: Fix one uninitialized conditional jump.
signal: Fix invalid strncpy usage in evalresp.

Here's another incorrect termination of the result of strncpy.
Additionally, there is no check to ensure the length of copied data is
not larger than the static buffer.
signal: Fix invalid read in evalresp.

For empty strings, line_len==0, and lcl_ptr+line_len-1 is one byte
before the beginning of the string. This happens to be some other random
variable, probably out_name in evresp_itp.
Merge pull request #832 from QuLogic/valgrind

Fix Valgrind issues