Fixed partial-files bug
Fixed partial-files bug

- Optimized Lookup() of children by storing them as a map by name

Silly me, fileById has to be a pointer to Node, or the ordering of the hash
results in arbitrarily missing data based on when the copy of Node{} into the
parent happens.

devilmonastery/fuse_gdrive,hatchling/fuse_gdrive,hatchling/fuse_gdrive,asjoyner/fuse_gdrive,asjoyner/fuse_gdrive,devilmonastery/fuse_gdrive