dname: add output buffer parameters to knot_dname_to_str
dname: add maximal label length constant
dname: unify comment style

Conflicts:
	src/libknot/dname.c
dname: add output buffer parameters to knot_dname_from_str
tests: extend dname tests
dbg: replace knot_dname_to_str with knot_dname_to_str_alloc
Merge branch 'master' into dname_str_params
dname: post review improvements
Merge branch 'dname_str_params' into 'master'

Dname str params

See merge request !282
Merge branch 'master' into lowercase

Conflicts:
	src/knot/dnssec/nsec3-chain.c