Free42 with local variables

[Thomas Okken]

I added support for local variables in Free42. Since this is brand new functionality, which required some significant changes in various low-level functions, I would like to test this a bit more before making an official release, but for the curious, I put test builds at https://thomasokken.com/free42/download/test/

There is some explanation in this thread over at the SwissMicros forum: https://forum.swissmicros.com/viewtopic....=10#p10430

There are non-backwards-compatible changes to the state file format, so I recommend backing up your state file before trying this.

[Thomas Okken]

Update: 2.1.3: fixed memory corruption bug in SOLVE and INTEG, caused by the new stack logic.

[Thomas Okken]

Update: 2.1.4: Android only: fixed bug in state file reading that caused State File Corrupt

[Thomas Okken]

I did a bit more polishing, couldn't find any more bugs. I think it's ready. I removed the test builds from my site and I'm releasing the official version 2.2.