Adds LZO1X999 compressor and fixes a holdover buffer bug

I've noticed that lzo-core has infrastructure for, but no implementation of LZO1X999, so I took an effort to implement it. The implementation was created by running lzo1x_9x.c from LZO2.05 through GCC preprocessor, manual syntactic correction, changing pointer semantics to array manipulation, and finally removing some dead code. Resulting compressor accepts compression levels 1 to 9, although, according to the original, only levels 7-9 are practical. Running speed is slightly slower than C version, usually requiring 2-3 extra seconds for large files. Existing tests were extended and seem to pass normally.