Fix expected output for test_1e.

TestRecord.test_1e tests whether rdrecord is able to read a signal in
format 24.  Since format 24 was previously implemented incorrectly,
the file containing the "expected output" needed to be wrong in order
for the test to pass.

Replace 'tests/target-output/record-1e' with the actual result of
'rdsamp -r sample-data/n8_evoked_raw_95_F1_R9 | cut -f 2-', compressed
using gzip.  (numpy.genfromtxt recognizes the '.gz' suffix and
decompresses it automatically.)

Since rdsamp displays -32768 for invalid samples regardless of the
format, whereas 'd_signal' retains the raw value (which is -2**23 for
invalid samples in format 24), we furthermore need to replace -32768
with -2**23 before comparing these two arrays.

Author: Benjamin Moody