OUTPUT *** buffer overflow detected *** because of output file name to be long

[Jemma1um]

When I ran mcluster with the following command, I got an error:
./mcluster -P1 -s0 -D1.0 -o 'mcluster_d1.0_N800_v1' -N 800

-----OUTPUT-----
*** buffer overflow detected ***: ./mcluster terminated
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7fb7239fa7e5]
/lib/x86_64-linux-gnu/libc.so.6(__fortify_fail+0x5c)[0x7fb723a9b56c]
/lib/x86_64-linux-gnu/libc.so.6(+0x116570)[0x7fb723a99570]
/lib/x86_64-linux-gnu/libc.so.6(+0x115ad9)[0x7fb723a98ad9]
/lib/x86_64-linux-gnu/libc.so.6(_IO_default_xsputn+0x80)[0x7fb7239fe6b0]
/lib/x86_64-linux-gnu/libc.so.6(_IO_vfprintf+0x139b)[0x7fb7239d150b]
/lib/x86_64-linux-gnu/libc.so.6(__vsprintf_chk+0x84)[0x7fb723a98b64]
/lib/x86_64-linux-gnu/libc.so.6(__sprintf_chk+0x7d)[0x7fb723a98abd]
...

I changed line 4792 of main.c, inside output3, from char tablefile[20] to char tablefile[50], to make sure that sprintf works well with long file names. Then I remake mcluster and it works.

Definitely, a shorter name can simply avoid this!

[cmaureir]

I opened a pull request that will solve this issue #12, mainly increasing a bit more the size of the buffers since it will cause no harm