ensureDir() did not handle one last error case and there was some logic
in the main() function that belonged to ensureDir() as well. It was also
creating a directory with a hardcoded 0700 mode, regardless of what mode
was passed to it.
This refactors it a little to fix the broken behavior, avoid redundant
checks by taking advantage of the behavior of MkdirAll, and move the
extra logic from main() into ensureDir().
The main() function is growing too big (142 lines as of the date of this
commit), so this attempts to extract some functionality out of there and
into their own functions to make it easier to reason about them and keep
functions short and concise.
--browser-only assumes syncthing is already running and will open the
user's browser in the URL:port currently used in the configuration if
the GUI is enabled.
Every time a JSON object is returned in an HTTP response, the
appropriate header needs to be set and the object itself needs to be
encoded. Doing this in every function is repetitive and error prone
(getDBFile and postDBScan, for instance, never set any headers).
This adds a helper function to centralize the appropriate JSON response
handling.