Create portable version

[chrisn]

We had a request to create a portable version of BeebEm, i.e., one that can run from any folder and doesn't need to be installed into Program Files.

[insleys]

Is this related to the recent CR about changing behaviour of switches to load/update settings? BeebEm can already be installed outside of Program Files, so that's misleading, but to be truly portable there must be no use of the Registry to store settings (or anything else).

Is this really a request to remove the dependency on the Registry? If so, the solution must allow for configurable settings/temp directories. An application cannot write files in its own directory without elevated privileges, so the typical interpretation of "portable" would require installation outside of Program Files or other protected folders unless there was a second option to write/store settings etc outside, e.g. in AppData<user>\Local\blah.

[chrisn]

It was just a suggestion to explore: https://twitter.com/0xC0DE6502/status/1348279193633775619, not directly related to the -CustomData option we recently added. I haven't given this any thought so far, so just wanted to capture the idea.