{mach,core}: move core sources to libs/core

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

src/engine.zig

@@ -1,54 +0,0 @@
-const std = @import("std");
-pub const Core = @import("Core.zig");
-pub const gpu = @import("gpu");
-pub const ecs = @import("ecs");
-
-/// The Mach engine ECS module. This enables access to `engine.get(.mach, .core)` `*Core` APIs, as
-/// to for example `.setOptions(.{.title = "foobar"})`, or to access the GPU device via
-/// `engine.get(.mach, .device)`
-pub const module = ecs.Module(.{
-    .globals = struct {
-        core: *Core,
-        device: *gpu.Device,
-    },
-});
-
-var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-const allocator = gpa.allocator();
-
-pub fn App(
-    comptime modules: anytype,
-    comptime app_init: anytype, // fn (engine: *ecs.World(modules)) !void
-) type {
-    // TODO: validate modules.mach is the expected type.
-    // TODO: validate init has the right function signature
-
-    return struct {
-        engine: ecs.World(modules),
-        core: Core,
-
-        pub fn init(app: *@This()) !void {
-            try app.core.init(allocator, .{});
-            app.* = .{
-                .core = app.core,
-                .engine = try ecs.World(modules).init(allocator),
-            };
-            app.engine.set(.mach, .core, &app.core);
-            app.engine.set(.mach, .device, app.core.device());
-            try app_init(&app.engine);
-        }
-
-        pub fn deinit(app: *@This()) void {
-            const core = app.engine.get(.mach, .core);
-            core.deinit();
-            allocator.destroy(core);
-            app.engine.deinit();
-            _ = gpa.deinit();
-        }
-
-        pub fn update(app: *@This()) !bool {
-            app.engine.tick();
-            return false;
-        }
-    };
-}