When creating files, instead of actually using GIT_FILEMODE_BLOB
and the other various constants that happen to correspond to
mode values, apparently I should be just using 0666 and 0777, and
relying on the umask to clear bits and make the value sane.
This fixes the rules for copying a template directory and fixes
the checks to match that new behavior. (Further changes to the
checkout logic to follow separately.)
The extended version of repository init adds support for many
of the things that you can do with `git init` and sets up
structures that will make it easier to extend further in the
future.
