At what Pari version did these happen?

[Dirk Laurie <dirk.laurie@gmail.com>]

I am revising a Pari-GP package I wrote in 2008 which would not
run under the current version, and the revision will not run under
the previous version. Accordingly, I wish to put version checking
in both versions of my package.

My question has three parts.

1. In what Pari-GP release did it become compulsory to use '||' instead
of '|'?
2. In what Pari-GP release did 'my' become available?
3. Are there any changes between 2008 and now that will make old
code that compiles without error behave differently?