Various changes/improvements: * Nicer init/deinit loop in Wiki class. * Renamed `wk cache` to `wk resolve`, made resolving pages a 1st class API on the Wiki class. * The `wk update` command now takes a path instead of an URL. * Re-implemented auto-updating pages when their file has changed. This added a new `isCacheValid` function on the DB layer. * Got rid of exceptions with some meta-properties being arrays and some not. Now they're all arrays, but there's some helper functions to work with that. * Remove trailing empty lines from multi-line meta-properties. * Fixed some issues parsing multi-line meta-properties and queries. * Fixed some issues resolving queries, especially with custom item templates. * Better handling of page/wiki permissions.