littleutils-1.0.21 released

Added new littleutils to-lzip and to-xz, which are markedly similar to to-lzma, except that lzip from LZIP and xz from the XZ utils are used instead.

Removed .7z-to-.lzma conversion capability from to-lzma. This was always fairly pointless, given the similarity in compression ratios. Removing it simplifies maintenance.