Simplified interface to bitbuffer.
Remove irrelevant values from GtBitbuffer.
Implement bits2store=0 case as initialization.
Made the bitbuffer interface more flexible.
documentation
cosmetics
fix warnings from scan-build
Fixed splint problem.
fix compiling with assert=no
add gt_desc_buffer_max_length()
store length of longest description in .des file
rework LTRdigest

This commit splits the former GtLTRdigest stream into multiple individual
visitors, making them more modular and more in style with the rest of
the Gt annotation processing machinery. Moreover this code changes the protein
domain detection component of LTRdigest to call HMMER externally instead of
linking to it (licensing and redistributability reasons).
output error on empty sequence
add sbgt target to Makefile
eliminate absolute paths in sbgt target
update make script
portability and compiler warnings

for portability see man getpagesize
add type to mapspec
add mapspec to compressed bitseq

fix to large class array, use direct bitseq, not compactulongstore
fix error with bitshifting by |w| bits

refactor, remove underscored functions

add save to and read from file to compressed bitsequence

and use intbits makros

optimize bits used
mapspec uses const char* instead of const GtStr*