Allow Ili9341 variables at the module scope

These statements no longer cause an error at the module scope:
let tft = initIli9321(9, 10)

Introduces a C++ subclass with a default constructor.
Workaround for nim-lang/Nim#14389

ili9341.nim

@@ -2,11 +2,12 @@ import pkg/nim-adafruit-gfx/gfx
 
 export gfx
 
-{.push header:"<Adafruit_ILI9341.h>".}
+{.push header: "workaround.h".}
+
 type
-  Ili9341 {.importcpp: "Adafruit_ILI9341".} = object of Gfx
+  Ili9341* {.importcpp: "Adafruit_ILI9341_Workaround".} = object of Gfx
 
-{.push importcpp: "Adafruit_ILI9341(@)", constructor.}
+{.push importcpp: "Adafruit_ILI9341_Workaround(@)", constructor.}
 proc initIli9321*(cs, dc: uint16): Ili9341
 {.pop.}
 

library.json

@@ -1,6 +1,6 @@
 {
     "name": "nim-ili9341",
-    "version": "0.1.0",
+    "version": "0.1.1",
     "license": "MIT",
     "dependencies": {
         "nim-adafruit-gfx": "https://github.com/markspanbroek/nim-adafruit-gfx",

workaround.h

@@ -0,0 +1,10 @@
+#include <Adafruit_ILI9341.h>
+
+// Adds a default constructor to Adafruit_ILI9341, to work around this issue:
+// https://github.com/nim-lang/Nim/issues/14389
+
+class Adafruit_ILI9341_Workaround : public Adafruit_ILI9341 {
+public:
+  Adafruit_ILI9341_Workaround(int8_t _CS, int8_t _DC): Adafruit_ILI9341(_CS, _DC) {}
+  Adafruit_ILI9341_Workaround(): Adafruit_ILI9341(-1, -1) {}
+};