Now app.command.ImportSpriteSheet() can be used from CLI

scripts/import_sprite_sheet_command.lua

@@ -0,0 +1,75 @@
+-- Copyright (C) 2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+do
+  local s = Sprite(8, 4, ColorMode.INDEXED)
+  assert(#s.cels == 1)
+
+  local i = s.cels[1].image
+  array_to_pixels({ 0, 1, 2, 3, 3, 2, 1, 0,
+                    1, 2, 3, 4, 4, 3, 2, 1,
+                    1, 2, 3, 4, 4, 3, 2, 1,
+                    0, 1, 2, 3, 3, 2, 1, 0 }, i)
+
+  app.command.ImportSpriteSheet{
+    ui=false,
+    type=SpriteSheetType.ROWS,
+    frameBounds=Rectangle(0, 0, 4, 4)
+  }
+  assert(#s.cels == 2)
+  expect_img(s.cels[1].image,
+             { 0, 1, 2, 3,
+               1, 2, 3, 4,
+               1, 2, 3, 4,
+               0, 1, 2, 3 })
+  expect_img(s.cels[2].image,
+             { 3, 2, 1, 0,
+               4, 3, 2, 1,
+               4, 3, 2, 1,
+               3, 2, 1, 0 })
+
+  app.undo();
+  app.command.ImportSpriteSheet{
+    ui=false,
+    type=SpriteSheetType.ROWS,
+    frameBounds=Rectangle(0, 0, 2, 3)
+  }
+  assert(#s.cels == 4)
+  expect_img(s.cels[1].image,
+             { 0, 1,
+               1, 2,
+               1, 2 })
+  expect_img(s.cels[2].image,
+             { 2, 3,
+               3, 4,
+               3, 4 })
+  expect_img(s.cels[3].image,
+             { 3, 2,
+               4, 3,
+               4, 3 })
+  expect_img(s.cels[4].image,
+             { 1, 0,
+               2, 1,
+               2, 1 })
+
+
+  app.undo();
+  app.command.ImportSpriteSheet{
+    ui=false,
+    type=SpriteSheetType.ROWS,
+    frameBounds=Rectangle(1, 1, 2, 2),
+    padding=Size(2, 0)
+  }
+  assert(#s.cels == 2)
+  expect_img(s.cels[1].image,
+             { 2, 3,
+               2, 3 })
+  expect_img(s.cels[2].image,
+             { 3, 2,
+               3, 2 })
+
+end