Version 12.0 Beta 3

3rd and hopefully last beta release of the upcoming v12.0 prog8 compiler.

changes since beta 2:

• assigning to an array indexed pointer is now possible. This requires the use of explicit pointer dereference though: pointer[index]^^.field = value
• added pointer array initializer size check
• various other additions and bugfixes not related to pointers perse, see the commit list v12.0-beta2...v12.0-beta3