-improved WASM compilation scripts

-added external bindbc.sdl import for WASM
-working on demos (WIP, working simple demo with ECS and SDL2)
-small change in ecs.std

demos/external/imports/bindbc/sdl/bind/sdlmessagebox.d

@@ -0,0 +1,75 @@
+
+//          Copyright Michael D. Parker 2018.
+// Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//          http://www.boost.org/LICENSE_1_0.txt)
+
+module bindbc.sdl.bind.sdlmessagebox;
+
+import bindbc.sdl.config;
+import bindbc.sdl.bind.sdlvideo : SDL_Window;
+
+enum SDL_MessageBoxFlags {
+    SDL_MESSAGEBOX_ERROR = 0x00000010,
+    SDL_MESSAGEBOX_WARNING = 0x00000020,
+    SDL_MESSAGEBOX_INFORMATION = 0x00000040,
+}
+mixin(expandEnum!SDL_MessageBoxFlags);
+
+enum SDL_MessageBoxButtonFlags {
+    SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT = 0x00000001,
+    SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT = 0x00000002,
+}
+mixin(expandEnum!SDL_MessageBoxButtonFlags);
+
+struct SDL_MessageBoxButtonData {
+    uint flags;
+    int buttonid;
+    const(char)* text;
+}
+
+struct SDL_MessageBoxColor {
+    ubyte r, g, b;
+}
+
+enum SDL_MessageBoxColorType {
+    SDL_MESSAGEBOX_COLOR_BACKGROUND,
+    SDL_MESSAGEBOX_COLOR_TEXT,
+    SDL_MESSAGEBOX_COLOR_BUTTON_BORDER,
+    SDL_MESSAGEBOX_COLOR_BUTTON_BACKGROUND,
+    SDL_MESSAGEBOX_COLOR_BUTTON_SELECTED,
+    SDL_MESSAGEBOX_COLOR_MAX,
+}
+mixin(expandEnum!SDL_MessageBoxColorType);
+
+struct SDL_MessageBoxColorScheme {
+    SDL_MessageBoxColor[SDL_MESSAGEBOX_COLOR_MAX] colors;
+}
+
+struct SDL_MessageBoxData {
+    uint flags;
+    SDL_Window* window;
+    const(char)* title;
+    const(char)* message;
+    int numbuttons;
+    const(SDL_MessageBoxButtonData)* buttons;
+    const(SDL_MessageBoxColorScheme)* colorScheme;
+}
+
+version(BindSDL_Static) {
+    extern(C) @nogc nothrow {
+        int SDL_ShowMessageBox(const(SDL_MessageBoxData)*,int*);
+        int SDL_ShowSimpleMessageBox(uint,const(char)*,const(char)*,SDL_Window*);
+    }
+}
+else {
+    extern(C) @nogc nothrow {
+        alias pSDL_ShowMessageBox = int function(const(SDL_MessageBoxData)*,int*);
+        alias pSDL_ShowSimpleMessageBox = int function(uint,const(char)*,const(char)*,SDL_Window*);
+    }
+
+    __gshared {
+        pSDL_ShowMessageBox SDL_ShowMessageBox;
+        pSDL_ShowSimpleMessageBox SDL_ShowSimpleMessageBox;
+    }
+}