[docs] Move roadmap to separate file

Author: elgopher

README.md

@@ -26,65 +26,21 @@ It's a game that resembles old 8-bit/16-bit games. This usually means:
 
 * Most API function names are similar and behave the same way.
 * Screen resolution is small, and the number of colors is limited. Although in Pi you can change the resolution and palette.
-* You have one small sprite sheet and a map.
+* You have one small sprite sheet.
 
 ### Why would I use it?
 
 Because it's the easiest way to write a game in Go. IMHO ;)
 
 ### Is Pi ready to use?
 
-Pi is under development. Only limited functionality is provided. API is not stable. See [roadmap](#roadmap) for details.
+Pi is under development. Only limited functionality is provided. API is not stable. See [roadmap](ROADMAP.md) for details.
 
-### How to get started?
+## How to get started?
 
 1. Install dependencies
-  * Go 1.18+
+  * [Go 1.18+](https://go.dev/dl/)
   * Pi is powered by [Ebitengine](https://ebiten.org/) which has its own dependencies. See [instructions](https://ebiten.org/documents/install.html) how to install them.
 2. Create a new game using provided [Github template](https://github.com/elgopher/pi-template). 
 
 See also [examples](examples) directory and [documentation](https://pkg.go.dev/github.com/elgopher/pi).
-
-## Roadmap
-
-* [x] Present game on the screen
-  * [x] ability to change the resolution and palette
-  * [x] sprite-sheet loader
-  * [ ] more options: full screen, specifying tps and scale
-  * [x] Game loop
-* [ ] Implement Graphics API
-  * [x] drawing sprites and pixels with camera and clipping support
-  * [x] add the ability to directly access pixels on the screen and sprite-sheet
-  * [x] palette transparency
-  * [x] palette swapping
-  * [ ] printing text on the screen
-    * [x] system font
-    * [ ] custom font and additional features: escape characters, offsets
-  * [ ] drawing shapes
-    * [x] rectangles, lines, circles
-    * [ ] fill patterns
-  * [ ] stretching sprites
-  * [ ] map API
-* [ ] math API
-  * [x] Cos, Sin, Atan2
-  * [ ] Min, Max, Mid
-* [x] Game controller support: gamepad and keyboard
-* [ ] Mouse support (dev mode)
-* [ ] Full keyboard support (dev mode)
-* [ ] Menu screen
-* [ ] Development console
-  * [ ] stopping, resuming the game
-    * [x] add a programmatic way to stop the game
-    * [ ] resume the game using console command
-  * [ ] scripting (running π functions)
-  * [ ] screen inspector
-  * [ ] sprite-sheet editor
-  * [ ] map editor
-  * [ ] sound editor
-  * [ ] music editor
-* [ ] Documentation
-  * [ ] Go docs
-* [ ] Examples
-  * [ ] simple programs for beginners
-  * [ ] interactive programs describing how functions work
-  * [ ] simple working game

ROADMAP.md

@@ -0,0 +1,43 @@
+## Roadmap
+
+* [x] Present game on the screen
+    * [x] ability to change the resolution and palette
+    * [x] sprite-sheet loader
+    * [ ] more options: full screen, specifying tps and scale
+    * [x] Game loop
+* [ ] Implement Graphics API
+    * [x] drawing sprites and pixels with camera and clipping support
+    * [x] add the ability to directly access pixels on the screen and sprite-sheet
+    * [x] palette transparency
+    * [x] palette swapping
+    * [ ] printing text on the screen
+        * [x] system font
+        * [ ] custom font and additional features: escape characters, offsets
+    * [ ] drawing shapes
+        * [x] rectangles, lines, circles
+        * [ ] fill patterns
+    * [ ] stretching sprites
+    * [ ] map API
+* [ ] math API
+    * [x] Cos, Sin, Atan2
+    * [ ] Min, Max, Mid
+* [x] Game controller support: gamepad and keyboard
+* [ ] Mouse support (dev mode)
+* [ ] Full keyboard support (dev mode)
+* [ ] Menu screen
+* [ ] Development console
+    * [ ] stopping, resuming the game
+        * [x] add a programmatic way to stop the game
+        * [ ] resume the game using console command
+    * [ ] scripting (running π functions)
+    * [ ] screen inspector
+    * [ ] sprite-sheet editor
+    * [ ] map editor
+    * [ ] sound editor
+    * [ ] music editor
+* [ ] Documentation
+    * [ ] Go docs
+* [ ] Examples
+    * [ ] simple programs for beginners
+    * [ ] interactive programs describing how functions work
+    * [ ] simple working game