mod(structure): update project structure

Remove examples, add description for design goals in README.md and
apply re-names and naming changes accordingly for the project structure.
Implement a flat hierachry, as the library shall remain pretty simple.

examples/container.zig

@@ -1,96 +0,0 @@
-const std = @import("std");
-const zterm = @import("zterm");
-
-const App = zterm.App(
-    union(enum) {},
-    zterm.Renderer.Direct,
-    true,
-);
-const Key = zterm.Key;
-const Layout = App.Layout;
-const Widget = App.Widget;
-
-const log = std.log.scoped(.container);
-
-pub fn main() !void {
-    errdefer |err| log.err("Application Error: {any}", .{err});
-
-    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .{};
-    defer {
-        const deinit_status = gpa.deinit();
-        // fail test; can't try in defer as defer is executed after we return
-        if (deinit_status == .leak) {
-            log.err("memory leak", .{});
-        }
-    }
-    const allocator = gpa.allocator();
-
-    var app: App = .{};
-    var renderer: App.Renderer = .{};
-    // TODO: when not running fullscreen, the application needs to screen down accordingly to display the contents
-    // -> size hint how much should it use?
-
-    var layout = Layout.createFrom(Layout.HContainer.init(allocator, .{
-        .{
-            Widget.createFrom(Widget.Spacer.init(allocator)),
-            15,
-        },
-        .{
-            Layout.createFrom(Layout.VContainer.init(allocator, .{
-                .{
-                    Widget.createFrom(Widget.Spacer.init(allocator)),
-                    25,
-                },
-                .{
-                    Widget.createFrom(blk: {
-                        const file = try std.fs.cwd().openFile("./src/app.zig", .{});
-                        defer file.close();
-                        break :blk Widget.RawText.init(allocator, file);
-                    }),
-                    50,
-                },
-                .{
-                    Widget.createFrom(Widget.Spacer.init(allocator)),
-                    25,
-                },
-            })),
-            70,
-        },
-        .{
-            Widget.createFrom(Widget.Spacer.init(allocator)),
-            15,
-        },
-    }));
-    defer layout.deinit();
-
-    try app.start(null);
-    defer app.stop() catch unreachable;
-
-    // App.Event loop
-    while (true) {
-        const event = app.nextEvent();
-        log.debug("received event: {s}", .{@tagName(event)});
-
-        switch (event) {
-            .quit => break,
-            .resize => |size| {
-                renderer.resize(size);
-            },
-            .key => |key| {
-                // ctrl+c to quit
-                if (Key.matches(key, .{ .cp = 'c', .mod = .{ .ctrl = true } })) {
-                    app.quit();
-                }
-            },
-            .err => |err| {
-                log.err("Received {any} with message: {s}", .{ err.err, err.msg });
-            },
-            else => {},
-        }
-        const events = try layout.handle(event);
-        for (events.items) |e| {
-            app.postEvent(e);
-        }
-        try layout.render(&renderer);
-    }
-}