Release 3.3.1

This is a production release that fixes a bug.

The bug was in the reporting of number length when the value was 0.

$ sha512sum bc-3.3.1.tar.xz
098bcbe0abc323b295bd46bcf8af00e69898ef560108b660964fb2dfdf6d114a17f051dde0fff06f06aa97f4cee086275eb5dc937166034d795d5cb3da999fca  bc-3.3.1.tar.xz

$ sha256sum bc-3.3.1.tar.xz
b6328ad691c71d1ae910dc3d45fe4b35faddd15f79b07b482e21b1766c89dda4  bc-3.3.1.tar.xz

$ stat -c '%s  %n'
229708  bc-3.3.1.tar.xz

$ sha512sum bc-3.3.1.tar.xz.sig
904a47bc565218d8243920f5c3c6b8a45a9f9914766fbba63730f926e7a08c3fbc28c2adcc23a3e08a4b1939375a5d766270415675afb7f9fe7b245ae498be1c  bc-3.3.1.tar.xz.sig

$ sha256sum bc-3.3.1.tar.xz.sig
585bf520d50bd6094573aef5ba223c642f5a77e8e643e9c015ca2b111e01d4e4  bc-3.3.1.tar.xz.sig

$ stat -c '%s  %n'
662  bc-3.3.1.tar.xz.sig