Convert hash file prefix from "~" to "%"

[mbullr]

Convert hash file prefix from "~" to "%"
Creating issue to document requirements for prefix change.

[mbullr]

Ref notes from WolWise1: #85 (comment)

[mbullr]

#85 (comment)

This is what qm does when attempting to logto account with "~" prefix:

Account (QM_MAB):
Account appears to use outdated subfile names. Use *FIXPFX to update.
Connection terminated

[WolWise1]

What did they do when they first moved over? It would have caused chaos if they'd had to do a complete swap-over on upgrade (or maybe not. They could have run that on all files as part of the upgrade).

Given that we don't have that luxury with Open Source (rolling upgrade is the norm), I think we need to handle both types together for a while at least. It shouldn't be that difficult?

And "resize" - as in "resize * * *" etc - still seems to me to be the best option for making the change :-)

[mbullr]

From latest QM ref manual Admin / Tools / fixpfx section:
... "Early releases of QM used the ~ prefix but it was discovered that some PC clean-up tools assumed that anything
beginning with a ~ character was a temporary item that could be deleted. QM release 2.7-1 (July 2008) changed the
prefix character to % to avoid this problem and automatically renamed the subfiles when opening a file for which
write permission was available. This renaming mechanism was removed in release 3.3-0 (April 2014) as there was a
small performance impact on all file open operations. Instead, the installer offered an automatic scan to update the
subfile prefix in all accounts. ..."

[mbullr]

There is a version of Scarlet that has the dyn file prefix changed from ~ to % at:
https://github.com/mbullr/ScarletDME/tree/prefix
This version does not contain any logic to convert older style accounts, but it should prevent you from logging into it.
Would like reviews prior to creating a pull request.