Add: TPABorder, Enhance AddOnTerminate

These changes are for Lape:

AddOnTerminate will now accept type methods such as
```
 AddOnTerminate('bmp.free');
````

The _CallProc is only a wrapper to there are on in/out variants because ffi currently does not act well with them (crashes...) I have spoken to niels about this and it should be fixed once there is a new ffi released but that could take some time.

Added TPABorder (Thanks to Slacky), which is quite simple as it returns the border of a TPointArray.

Don't accept this until  * SHA: 4ef17912fb980be2395e54ccb00ed8cfdd9afd6a
 has been merged, due to this commit requiring it.