Undo removal of SIGINT handler before launching mp Pool

Removing and adding back the signal handler causes an error when
running with multiprocessing from Matlab, and doesn't provide much
improvement in usability

euphonic/data/interpolation.py

@@ -250,16 +250,9 @@ def calculate_fine_phonons(
         # Try to create a multiprocessing pool first, in case it fails
         if nprocs > 1:
             try:
-                import signal
                 from multiprocessing import Pool
                 from functools import partial
-                # Temporarily remove SIGINT handler before creating pool, so
-                # child processes don't inherit it. Instead handle SIGINT
-                # (e.g. keyboard interrupts) from the main process only and
-                # terminate the pool before exiting
-                sigint_handler = signal.signal(signal.SIGINT, signal.SIG_IGN)
                 pool = Pool(processes=nprocs)
-                signal.signal(signal.SIGINT, sigint_handler)
             except RuntimeError:
                 warnings.warn(('\nA RuntimeError was raised when initialising '
                                'the multiprocessing Pool. This is probably due'

setup.py

@@ -17,7 +17,7 @@
 
 setup(
     name='euphonic',
-    version='0.1dev2',
+    version='0.1dev3',
     author='Rebecca Fair',
     author_email='rebecca.fair@stfc.ac.uk',
     description=(