Track local label scope, string equated as ..

[Rangi42]

Follow-up to #1499

Fixes #1503

[ISSOtm]

Yep, looks good. I imagine that the debugfile macros can now make use of this:

def TIGHTEST_SCOPE equs "."
rept -1
    if !def({TIGHEST_SCOPE}.)
        break
    endc
    redef TIGHEST_SCOPE equs "{TIGHTEST_SCOPE}."
endr
println "@ - {{TIGHTEST_SCOPE}} = ", @ - {{TIGHTEST_SCOPE}}

[ISSOtm]

(If this seems correct to you, then I'll let you merge this PR.)

[Rangi42]

That looks basically correct. You can't rept by a negative count so that should be rept $7fff_ffff; "TIGHEST_SCOPE" is a typo; and I would add a sanity check in case !def(.); but the use of ., .., etc is correct (which I tested on the two label levels we currently support).