Improve SyntaxTestHighlighterListener header handling
Improve SyntaxTestHighlighterListener header handling

1. The `self.header` is an object attribute and should be therefore declared in `__init__()`
2. The `self.header` is queried first in `__del__()` to avoid reading settings, if we are not within a syntax_test_...
3. Save 2 lines of code when checking syntax_test_ file name

SublimeText/AAAPackageDev,SublimeText/AAAPackageDev,SublimeText/PackageDev