all: more rootDecoder refactorization
utils: cycle is an int16.
utils: only accept 0-or-1 ';' in namecycle
all: introduce directory struct and root-directory concept into File.
test: update Directory test for better namecycle semantics
utils: datime2time
decoder: fix readInt16, add readInt64
ifaces: simplify Directory interface (use comma-ok idiom)
all: more impl.
Merge branch 'feature/refactor-decode-file' into develop