Merge pull request #10 from krzysztofwos/master

Minor changes: add .gitignore and export constructors of UnixDiffTime.
adding records for UnixDiffTime.
ver bumps up.
doc fix.
ver bump up.
FFI convention.
Define _GNU_SOURCE for strptime_l

Without this we get -Wimplicit-function-declaration warnings from GCC on
non-Linux glibc-based architectures.
Pass a valid locale name to newlocale

FreeBSD libc treats a NULL second argument to newlocale as equivalent to
"C", but glibc returns an error in that case, causing a segfault shortly
afterwards when passing a NULL locale to strftime_l/strptime_l.
Merge pull request #11 from cjwatson/master

Fix test failure on Debian GNU/kFreeBSD (and probably GNU/Hurd)
Make c_format_unix_time and c_format_unix_time_gmt return the total number of characters copied into the buffer.
Factor out memory allocation in formatUnixTime and formatUnixTimeGMT into a helper function. Change the maximum number of characters to be copied into the buffer to 80 and use the total number of characters copied to resize the buffer before building a ByteString.