Added function to compute lcps in xdrop algorithm.
Simplified xdrop lcp function.
Additionally check the leftsep and rightsep values.
Move xdrop-lcp function to seqabstract.
implement seqabstract lcp function with four loops.
Rename huffman.[ch] => huffcode.[ch] to avoid conflicts in ar.
If possible compute lcps via bivector comparison.
Remove countgt_encseq_compare_viatwobitencoding.
Allow to use two different encseqs when bitvectors.
Added prefix GT_ENCSEQ_ to 3 names of macros.
Remove unnecssary GtEncseq arguments in ltrharveststream.
Minizimed number of calls to gt_encseq_seqnum.
Simplified code by using pointers to repeats array.

- rename lmin/lmax in SubRepeatInfo to tsd_lmin, tsd_lmax
- add const annotation for several pointers args.
- code cosmetics
Replace pair of motifmismatchesleft/right LTR by struct

combine maximumsequence length with dmax value
Let xdrop only work on the current contig.
Let xdrop only work on single dbseq and queryseq.
Omit computation of leftsep and rightsep.
Simplified the check for decinding lcp-strategy.
Efficiently compute stoppos in reverse direction.
Where possible compute lcp using bitstring-ops.