Made the editor’s contents reflect the currently selected post in the sidebar.
Fixed the filter system so that it actually, you know, works.
Merge branch 'master' into editor
Made the editor disabled when no file is selected.
Made the editor able to save files.
Made the proxy icon/window title match up with the edited post.
Made site processing asynchronous.
Refactored feed processing into its own method.
Refactored post template loading into its own method.
Removed a couple unnecessary comments.
Added error handling to the post writing method.
Refactored source directory verification into its own method.
Refactored the raw default template into a private property.
Refactored source directory parsing into its own set of two methods.

Also added error handling to filter processing.
Gave a few errors more specific codes.
Further refactored raw default template loading.
Made the site processing method a bit more straightforward.
Fixed a file system race condition. This is why I should read the docs.
Small bits of cleanup in the site class, including better organization.
Removed an unnecessary @class declaration.