+BROKEN 1/x renaming a symbol in DataSource should change Bars.Symbol &save (WHILE STREAMING???)

-NO if Bar.HasParents Bar.Symbol=Bar.ParentBars.Symbol ? same with ScaleInteval
+TESTME DataSource.SymbolRename()
+TESTED DataSource.SymbolRename(), BarFileSave happens once, EachBarSymbolRename per-chart from Executor;

+BarFile v2 in action (fixedSize Strings) TODO: faster seek&write barAppend() and SymbolRename()
+using MOCK\[THIS1-minute]\RIM3_1-minute.bar for re-read and deleteAll
TODO create header structure and have its length the same both for Read & Write
+BarFile v3: AFTER_IMPLEMENTING_FIXED_SYMBOL_WIDTH_IGNORING_WHAT_I_READ_FROM_FILE

+DataSource "optimize file write time"
+TESTME BarAppend seek to the end, read last Bar, overwrite if same date or append if greater; 0.1ms instead of reading all - appending - writing all
+PROFILER_SAID_TOO_SLOW