AbstractGridCoverage2DReader: fix formatting and order
Refactor AbstractGridCoverage2DReader to remove all direct calls to the variables that assume one layer.
[GEOT-4681] SimplifyingFilterVisitor should eliminate constant binary comparisons
[GEOT-4680] PostPreProcessFilterSplittingVisitor throws Exception with complex logic filter with null literals
Grid Coverage: Fix error in refactoring methods.
Merge pull request #354 from NielsCharlier/coveragereader

Refactor AbstractGridCoverage2DReader