Add --disable-lzo configure option
Search for lzo/lzo1x.h, lzo2/lzo1x.h and lzo1x.h.
Support and autodetect LZO version 2.0 and later.
Remove autogen.sh, the autoreconf program does exactly that. Update everything for the latest autoconf and automake versions.
Use CPPFLAGS, LDFLAGS and LIBS as appropiate.
Update configure scripts.
Fix warning and add missing checks for LZO library.