DiagConsumer::Begin/EndSourceFile() are used to switch from "parsing command...

DiagConsumer::Begin/EndSourceFile() are used to switch from "parsing command line flags" to "parsing source files" more; not to signal a new source file to the diag client.
Switch BeginSourceFile() on after having parsed Interpreter internals.
Switch it off (EndSourceFile()) in ~Interpreter.
Indentation.

Now that we handle diags appropriately, test/ErrorRecovery/MetaProcessor.C fails; repair it.


git-svn-id: http://root.cern.ch/svn/root/trunk@47476 27541ba8-7e3a-0410-8455-c3a389f83636