remove stray abort() call; ok stsp

when finding changed paths iterate tree entries in on-disk order for speed ok op, jamsek

remove unused function got_read_file_to_mem()

remove dependency of gitwrapper, gotctl, and gotsh on object_parse.c Move some functions from object_parse.c into hash.c. These functions either require hash.c code anyway or contain object ID implementation internals. Add a new file object_qid.c, for got_object_id_queue and got_object_qid. This new file must be linked to virtually every program.

add support for protecting references against 'got send -f' to gotd ok op@

add some helper functions to compute hashes This adds a set of functions to abstract over SHA1Init, SHA1Update, SHA1Final, their respective SHA256 variants and how to compare digests. Replace all the SHA1*() usage with the new APIs. It's a preparatory step for sha256 handling. ok stsp@

provide functions to parse/serialize different hashes it abstracts over the hash type and ensures that object ids are zero'ed before their sha1 digest is written. Needed by the incoming sha256 support. ok stsp@

rename lib/sha1.c to lib/hash.c It will soon grow functions to deal with sha256 too. stsp@ agrees.

include sha2.h too where sha1.h is included In preparation for wide sha256 support; stsp@ agrees. Change done mechanically with find . -iname \*.[cy] -exec sam {} + X ,x/<sha1\.h>/i/\n#include <sha2.h>

introduce got_error_checksum ok stsp@

introduce got_object_id_hex to replace some got_sha1_digest_to_str() It's an analogous to got_object_id_str but writes to the given buffer. ok + improvements by stsp@

use got_object_id_cmp instad of memcmp where possible in object_parse.c ok stsp@

fix typo: overlapping comparison always evaluates false ok stsp@

always cast ctype' is*() arguments to unsigned char ok stsp@

remove trailing whitespace; patch by Josiah Frentsos