rename sha1.c to hash.c

include sha2.h where sha1.h was included

sed -i s/sha1/hash not exactly, some "hash" were changed back to "sha1" for the time being.

got_imsg_fetch_ref: use struct instead of buffer for id ok stsp@

got_imsg_fetch_have_ref: use struct instead of buffer for id ok stsp@

replace malloc+memcpy with strndup. no functional change intended ok stsp@

got: minor refactor of got_pathlist_free() API Accept flag parameter to optionally specify which pointers to free. This saves callers looping through the list to free pointers. ok + fix stsp@

fix uninitialised fildes variables in libexec helpers Reviewed and uncovered as part of the diff in the forthcoming commit (pathlist API refactor). ok stsp@

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

make 'got clone -b' work for repositories which lack a HEAD reference ok op@

avoid looping over SHA1Update() in got-fetch-pack; suggested by millert@

got-fetch-pack: fix wrong memmove length leading to dubious checksum failures ok millert tracey

remove trailing whitespace; patch by Josiah Frentsos

fix snprintf error handling follow the "proper secure idiom" described in the CAVEATS section of printf(3). reminded by tb@ and millert@

convert two snprintf to strlcpy "looks good to me" millert@