Add AUTO, RENUM, DELETE, COMMON; fix LIST range parsing

AUTO generates line numbers during interactive editing, RENUM
renumbers program lines and patches all GOTO/GOSUB/ON references,
DELETE removes line ranges. COMMON declares variables preserved
across CHAIN. Also fixed LIST/DELETE range parsing (was broken by
expression evaluator consuming the dash as subtraction).

Bump to v0.7.0, 53 tests.

tests/programs/common_target.bas

@@ -0,0 +1,5 @@
+10 REM Target for COMMON test
+20 IF X = 42 THEN PRINT "X preserved" ELSE PRINT "FAIL: X lost"
+30 IF N$ = "hello" THEN PRINT "N$ preserved" ELSE PRINT "FAIL: N$ lost"
+40 IF Y = 0 THEN PRINT "Y cleared" ELSE PRINT "FAIL: Y kept"
+50 PRINT "COMMON test passed"