src/generate-chirp.c : Default amplitude is now 1.0.

Fixes https://github.com/erikd/sndfile-tools/issues/13
Move src/kaiser_window_test.c -> tests/kaiser_window_test.c.
pre-commit hook : Handle renamed files.
Add function parse_int_or_die() with tests.
Use parse_int_or_die() instead of atoi() where appropriate.
src/generate-chirp.c : Fix default sweep start and end frequencies.

Fixes https://github.com/erikd/sndfile-tools/issues/12
Merge branch 'master' into devel