pyssel's README held the engine's manual, 2,482 lines of it. It is here
now, a page for each part: getting started, the engine's core, drawing,
scenes, the user interface, and games and the editor, linked from Home
and the sidebar. The examples keep a game's state in its nodes and
resources, finding a form's or a layout's parts by their paths and
connecting signals to functions given the node, and one variable each
for what they start, the REPL's way in. They follow the code as it is
today: exact colour types, the property metaclass's checks of initargs,
a theme's change reaching its session's trees, BUTTON-PRESSED,
VIEWPORT-FULLSCREEN and PROJECT-FAVORITE.
