Updated to work with nim 0.20

- Attempt to fix deprecated this:self pragma by injecting self to methods and properties (needs more testing)
- Changed import headers to use / (slash) instead of . (period)
- Fixed object branch in godotapigen.nim
- Fixed deprecated nimNode.ident with nimNode.strVal

Fix toGodotName function

Consider procCall calls as special cases, otherwise it gives problems in _init function

Fix infinite recursive call in Godot 3.2

godot/gdnativeapi.nim

@@ -1,6 +1,6 @@
 # Copyright 2018 Xored Software, Inc.
 
-import internal.godotinternaltypes, core.godotcoretypes, macros
+import internal/godotinternaltypes, core/godotcoretypes, macros
 
 type
   ColorData* {.byref.} = object
@@ -3593,7 +3593,7 @@ proc setGDNativeAPIInternal(apiStruct: pointer, initOptions: ptr GDNativeInitOpt
       # Not used
       discard
 
-  if not header.next.isNil:
+  if not header.next.isNil and header != header.next:
     setGDNativeAPIInternal(header.next, initOptions,
                            foundCoreApi, foundNativeScriptApi)